- Email: [email protected]
Productivity and economic viability of snakehead Channa striata culture using an aquaponics approach
Aquacultural Engineering 89 (2020) 102057
Contents lists available at ScienceDirect
Aquacultural Engineering journal homepage: www.elsevier.com/locate/aque
Productivity and economic viability of snakehead Channa striata culture using an aquaponics approach
T
Tran Thi Ngoc Bicha,c, Doan Quang Trib,*, Chen Yi-Chinga, Huynh Dang Khoac a
Environmental Engineering Department, Da-Yeh University, Changhua, Taiwan Sustainable Management of Natural Resources and Environment Research Group, Faculty of Environment and Labour Safety, Ton Duc Thang University, Ho Chi Minh, Viet Nam c Tra Vinh University, Tra Vinh, Viet Nam b
A R T I C LE I N FO
A B S T R A C T
Keywords: Green agriculture Applied aquaponics Snakehead Water spinach Climate change
This study was carried out to investigate the viability of utilizing aquaponic technology in culturing local fish: snakehead Channa striata and water spinach Ipomoea aquatica. Snakehead was raised for 150 days in a floating plastic pond with an area of 3 × 4 × 1.2 m having a capacity volume of ∼14.4 m3. Fish were randomly arranged into two experimental systems at density of ∼0.3 kg fingerlings/m3 e.g. SAQ – snakehead in aquaponics; SC – snakehead in normal system where control ponds were continuously aerated with ∼20% daily exchange of water. Fish were fed commercial feed twice a day. Initial results showed that in aquaponics compared with normal systems the SAQ efficiency exhibited 70% water exchange; five times lower in NH3 level: (0.01–0.03 mg/ L vs. 0.05–0.16 mg/L); three times lower in NO2 level: (0.28–0.58 mg/L vs. 0.56–2.59 mg/L). Snakehead production was significantly higher in aquaponics with higher survival ratio of fish: 99.76% vs. 71.40%; ∼3 times higher in fish yield: 366 kg vs. 130 kg. The production of water spinach was also elevated in aquaponics versus normal systems 406.4 kg vs. 188 kg. The total income from snakehead and water spinach in SAQ were 4 times higher than in normal farming systems: 1219.42 $US and 307.04 $US. Based on the results of the current study, it is expected that applying aquaponics utilizing local available materials and species will enhance the sustainability of the overall system and keep the aquaponics lasting and expanding to social life especially on sustainable culturing snakehead Channa striata.
1. Introduction In Asia countries, snakehead Channa striata is a popular carnivorous freshwater fish with high value in the market because of the firm, white and boneless tasty flesh and flavor (Walter et al., 2004; Sinh et al., 2014) and the uses of fish for medicinal purposes (Sahid et al., 2018; Wahab et al., 2015). Cultured snakehead has become an economically important freshwater fish in developing countries as Thailand, Malaysia, Indonesia, Bangladesh, India and Vietnam. In 2016, the total global capture and aquaculture production of snakehead Channa striata reached 92,523 t (FAO, 2019). In Vietnam, snakehead has been cultured for 60 years and becomes an important species in Mekong Delta. The production of snakehead in Vietnamese Mekong Delta increased from 5300 to 40,000 t (2002–2009) (Chung and Sinh, 2011). An Giang, Dong Thap, Hau Giang, Vinh Long, and Tra Vinh are provinces dominating of culturing snakehead (Long, 2010). In Tra Vinh province, the area of farming snakehead has been continuously increasing and
⁎
reaching 30,000 t in 2018. In 10 years, the area of farming snakehead has expanded from 61 ha to 270 ha (2010–2018) (Tra Vinh GSO, 2019). Intensive culture of snakehead has resulted in increased feed and chemical input into natural water bodies that negatively affects water quality. The traditional farming systems of snakeheads have mainly used live feed or industrial feed with high protein ratio (∼30%–40%). Almost the waste from intensive snakehead ponds directly drain to the environment causing serious environmental pollution and the depletion of natural aquatic resources in freshwater. Furthermore, according to a report by Tra Vinh Department of Natural Resource and Environment, 2018, most of intensive cultured snakehead has been using groundwater to supply water source to ponds that cause depletion of freshwater resources. Additionally, combined with climate change, the salinization and pollution of watercourses and bodies, and the increased degradation of water-related ecosystems, freshwater scarcity is growing critically. Moreover, food security is recognized as most concerning issue
Corresponding author. E-mail address: [email protected] (D.Q. Tri).
https://doi.org/10.1016/j.aquaeng.2020.102057 Received 26 June 2019; Received in revised form 16 October 2019; Accepted 15 January 2020 Available online 24 January 2020 0144-8609/ © 2020 Elsevier B.V. All rights reserved.
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
and adapting to climate change in the future.
related to population growth. To increase food demand, as other developing countries, Vietnam has promoted the use of pesticides to increase the yield of agricultural products, especially in vegetables (Pham et al., 2016). Recently, announcements on food poisoning by unsafe vegetables have been exposed and widely broadcast in media in Vietnam. Eating foods contaminated with pesticides or other chemicals had increased the cause of cancer e.g., 125 000 new cases of cancers (2012) (140 cases per 100 000 population) and predicted to increase to 190 000 new cases by 2020, when 75 000 deaths will result from cancers per year (84 deaths per 100 000 population) (Nguyen et al., 2017). The Vietnam Ministry of Health, 2016 reported that there were 677 incidents of food poisoning that affected more than 21,000 people (2011–2014). Therefore, to demand for healthy and environmentally friendly food, many Vietnamese consumers willing to pay more for organic or safe food (Simmons and Scott, 2007; Truong et al., 2012; De Koning et al., 2015) Aquaponics could play in producing healthy and sustainable food. Aquaponics now is considered as a sustainable fishery/agricultural model in terms of enhancing the productivity by allowing the sustainable growth of two crops in one system. Aquaponics is a combination of aquaculture and plant cultivation to enhance productivity through the achievement of the symbiotic interaction in reducing the need of chemical fertilizer for plant and the discharged water (Rakocy et al., 2006). Safe and friendly to environment: the mechanical process of the model is based on a circulating biological filtration rules: wastewater from aquariums (containing wastewater) is fed to vegetables. The vegetable bed acts as a circulating biological filtration system: they absorb waste from the aquarium and supplies clean water return to the fish tank. There are numerous researches focusing on aquaponics techniques; type of aquaponics; The comparison on the economics, environmental and social benefits of aquaponics. Lacking in the literature is a study focusing on utilize local materials as well as local species to aquaponics system to reduce investment cost to increase the income, especially using snakehead Channa striata in aquaponics. Moreover, there has been little focus on how to apply aquaponics in developing countries with low – income where is organic food/safe food still very expensive and impossible to build it in rural area or urban cities. Besides, to supply enough food to human requirement, intensive aquaculture systems are developing rapidly, and most located in developing countries where the major crisis with climate change, pollution and water depletion are felt. Normally, tilapia is the most popular species to culture in aquaponics systems. Recent efforts by researches have focused on replacing tilapia with other aquatic species with high market value such as Catfish (Hasan, 2014); Trout (Petrea et al., 2013); African Catfish (Mamat et al., 2016); Silver catfish (Da Rocha et al., 2017). However, little work has been conducted in Vietnam or globally to apply and promote the rearing and culture techniques of snakehead in aquaponics combining with utilize available local materials as coconut peat, rice husk, water hyacinth roots, bamboo tree, Styrofoam, canvas, etc., to reduce investment cost to increase the potential income to local farmers. Therefore, it is a need to conduct a study covering all the aspects of snakehead fish industry by applying aquaponics to build green agriculture and improve quality and quantity of food production. The purpose of the study is culturing high market value fish snakehead Channa striata in aquaponics to increase the productivity and profits to farmers. The most importance of applied aquaponics is ultimately reused and recycled local materials to reduce initial investment cost and culture local high value species to increase the potential profits that strongly attract farmers investment. The results of this study will be potential to enhance the quality and quantity of industrial farming snakehead not only in Vietnam but also productive to other countries developing in commercially culturing snakehead. Furthermore, the conducted results of our study potentially contribute to develop new and local design of aquaponics suitable to culture high value local species to keep the aquaponics lasting and expanding to social life to saving more water and improving food production to feed the world
2. Methodology Our experiment design was based on the local conditions and the future sustainable farming systems to build up the new farming system more adapted to climate changing and increase the quality and quantity of food source. We collected the data from GSO Tra Vinh and went to the field to do the survey on the current situation of locally culturing snakehead, local materials, the policy and potential to develop intensive system but sustain and friendly to environment. Our purpose was primarily designed and explored the potential of apply aquaponics to culture snakehead industrially. Further, we also desired to apply aquaponics at low – income area to develop the low cost and friendly farming systems to improve food security and food production. 2.1. Study area Tra Vinh province which is belonging to Vietnamese Mekong Delta is coastal area strongly developing in intensive aquaculture. In Tra Vinh province, the area of farming snakehead has sharply increased in recent years. In 10 years (2010–2018), the area of farming snakehead is expanded to 5 times from 61 ha to 270 ha. Normally, snakehead is intensively cultured in ponds by farmers who utilize daily exchanges of water and use significant amounts of chemicals to prevent and treat the disease. This farming method has caused serious negative impact to water resources and polluted the environment. Moreover, Tra Vinh province is one of coastal provinces of the Vietnamese Mekong Delta where agricultural water demand is an extreme issue due to sea level rise that affects most on freshwater intensive culture. Some areas have been seriously affected by sea level rise and salted the soil. In Vietnamese Mekong Delta and other Asia countries, there are abundant sources of coconut husk, rice husk and other agricultural materials can replace the base soil in developing the agriculture. Therefore, it is necessary to apply aquaponics to culturing snakehead combining with utilize available local materials in newly design aquaponics systems to keep the systems more friendly to environment and advantage in productivity and economic viability. The study was conducted in an aquaponics farm of Saphenix Co., Ltd. at Luong Hoa village, Chau Thanh district, Tra Vinh province, Vietnam for a period of 150 days: 02/10/2018 – 07/15/2018. The systems were designed in the net house with 6 floating plastic ponds (3 × 4 m) and 6 vegetable beds (8 × 3 m) (Figs. 1 and 2). The arrows in Fig. 1 showed the flow of water. Water flowed from fishpond to filter tank to vegetable bed. Then, water run thoroughly from the top of the vegetable bed and returned clean water to fishponds via the drainage system at the end of the vegetable bed. 2.2. Experimental design 2.2.1. Aquaculture Fingerlings of snakehead (Fig. 3) were collected from hatchery in Dong Thap province, Vietnam with averaged weight 5.36 ± 1.54 SD g and length 8.53 ± 1.04 SD cm. Before stocking, fish were disinfected by bath treatment of 5 ppm KMnO4. Snakehead was cultured in floating plastic ponds with an area of 3 × 4 m and water level 1.2 m depth having a capacity of 1440 L. Each pond had inlet and outlet facilities connected to the bio- filter system locating along the side of the system. The bio-filter tanks were design with layers from the top to the bottom of filter tank: gravel 4 × 6, gravel 1 × 2, sand and cap of water bottle mixing with pieces of cutting net. Each layer was put in a net bag that could easy to arrange, wash and exchange. For fingerlings stocking, firstly, we scaled one kilogram of fingerlings with triplication. Secondly, we counted number of fingerlings per kilograms. Then, fish were randomly arranged into two experimental systems at stocking density of ∼0.3 kg fingerlings/m3 (70 fish/m2) SAQ – snakehead in aquaponics; 2
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Fig. 1. The layout of the experimental design (SAQ snakehead in applied aquaponics; SC was snakehead cultured in ordinary system as the control pond; VC presented water spinach growing in ordinary condition as the control experiment).
SC – snakehead in control ponds following the normal or traditional snakehead culture which were continuously aerated with about 20% daily exchange of water. In normal culture systems, water in pond is exchanging daily at least 20%: pumping water in pond out to environment without treatment and then add the same amount of soaking out back to the pond. Each treatment had three assigned replications. Data for all water exchange events were recorded. During the study period surface water from river was the main source of water to the aquaria. The water from river was pumped to the supplying water pond and treated with 5 ppm KMnO4 before adding to the cultivating systems. Aeration pump was used to maintain adequate level of dissolved oxygen ∼4 mg/L. Fish were fed commercial feed at the average ratio at 5% of fish body weight. The fish were manually fed twice a day (07:00 am and 05:00 pm) with a commercial compound feed in the form of extruded pellets (Viet Thang feed, Vietnam; composition: 40% crude protein, 6% crude fat; 5% crude fiber, 16% ash, 2.5% NaCl, 2.5%
calcium, and 1% calcium/phosphorus, as-fed basis). Fish were fed 6 days continuously and then took one day without feeding to promote food digestion more efficiency. The lengths and weights of 50 live fish/ pond were recorded one time/month during the culture period. After 150 days, all fish were harvested by the market size (Fig. 4). The growth performances of snakehead Channa striata was calculated using formula (1), (2), (3) and (4).
Survival rate (Pauly 1980) =
No. of total fry obtained × 100 No. of total fry stocked
Length gain = Final body length (cm) − Initial body length (cm)
(1)
(2)
Weight gain (g) = Final body weight (g) − Initial body weight (g) (3)
Fig. 2. (a) Applied aquaponics experiments; (b) Automatic water pumping systems; (c) Illustrated vegetable bed; (d) Floating plastic pond; (e) Water from vegetable bed returning fresh and clean water back to the fish tank; (f) Water spinach grow well in applied aquaponics. 3
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Fig. 3. Snakehead fingerlings.
Fig. 4. Snakehead got the market size 400−500 g/fish after 150 days of culturing.
FCR (Castell and Tiews 1980) =
Total feed used (kg ) Final body wt (kg ) − Initial body wt (kg ) (4)
Water quality parameters temperature and pH were tested twice daily in the morning (07:00–08:00 am) and in the afternoon (14:00–15:00 pm) with the help of pH meter pen type AZ 8685 (Taiwan). Other water quality parameters: O2, NO2, NH3, Alkalinity were recorded 1 time per week throughout the culture period by Sera test kit (German), LAQUAact DO110 (Japan), Hanna Checker Colorimeters. 2.2.2. Agriculture The applied aquaponics was constructed by using available local materials to reduce the investment cost as well as increasing the profits to local farmers. Six round 24 m2 (8 × 3 m) plastic bed were prepared for growing water spinach Ipomoea aquatic (Fig. 2a). Vegetable bed was designed by reusing the Styrofoam which was containers of baby shrimp. The frames of vegetable bed were strongly holding by bamboo trees which was very cheap and grown at farmer’ garden. The vegetable bed (Fig. 2c) was designed many layers as a filter system from bottom to the top the first layer: gravel 4 × 6 cm; the second layer: gravel 1 × 2 cm and the third layer: coconut peat. Each layer was separated by HDPE net 64 mesh (200 holes/cm2). Coconut peat was used as the base soil to grow water spinach. The seedlings were placed into the holes: three seeds per hole. The space between each hole was 4–6 cm (Fig. 5). Water is automatically timing pumping 6–10 times/day (3–8 h/day) depending on the growth of fish and plants. In ordinary planting system, water spinach was watering two times per day. Fertilizers is used for every 10–15 days. Some chemicals as Aztron, Dithane 80WP, Sumicidin 10EC are used to treat the worms. However, in this
Fig. 5. Water spinach in normal farming system. Coconut peat was used as a based soil to grow water spinach. The seedlings were placed into the holes: three seeds per hole. The space between each hole was 4−6 cm.
experiment, the normal planting systems which acted as control system, watering was done as normal twice a day at 8:00 am and 4:00 pm until water drained from the bottom of the raised beds. Fertilizers and chemicals were not used in the planting control systems. The experiment was triplicated. Plant growth parameters measured were final biomass. Experimental time was recorded as number of days after sowing (DAS). At 24 DAS all the plants ranging from 35 to 45 cm (Fig. 6) in height were cut at ground level and above ground biomass measured. After next 10 days, we harvested another round of water spinach. All the harvested water spinach was raw weight. Then, we raked and turned up the coconut peat and added some more coconut peat to keep them
4
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Fig. 6. Water spinach were cut at ground level at 24 DAS all the plants ranging from 35 to 45 cm in height.
3. Results and discussion
156.88 ± 19.79 mg/L CaCO3 (SAQ) and 106.56 ± 17.28 to 116.38 ± 16.39 mg/L CaCO3 (SC). During the experiment the ammonia value (NH3) varied from 0.01 ± 0.002 to 0.03 ± 0.003 mg/L (SAQ) and 0.05 ± 0.034 to 0.16 ± 0.11 mg/L (SC). The values of Nitrite (NO2) values were recorded in the spread of 0.28 ± 0.25 to 0.58 ± 0.41 mg/L (SAQ) and 0.56 ± 0.71 to 2.59 ± 1.52 mg/L (SC). All the physical and chemical parameters of the rearing water were found to be in the optimum range required for aquaculture practice in the freshwater aquaculture by Boyd (1990a,b) except the value of Nitrite in treatment experiment (SC) starting from the second month of farming period: nitrite concentration > 1.0 mg/L, especially in the afternoon.
3.1. Water quality and parameters
3.2. Water efficiency
All water parameters were within tolerable limits except the value of Nitrite in control treatment (SC). Table 1 showed the results of water quality parameters in two treatments during the study period (mean values ± standard deviation). The water temperature was recorded from 28.05 ± 0.67 to 31.75 ± 0.76 °C (SAQ) and 26.34 ± 1.03 to 33.47 ± 1.74 °C (SC). The pH ranged from 6.9 ± 0.1 to 7.8 ± 0.2 (SAQ) and 7.2 ± 0.2 to 8.0 ± 0.2 (SC). The dissolved oxygen was found 4.9 ± 0.4 to 6.9 ± 0.3 mg/L (SAQ) and 3.5 ± 0.5 to 5.5 ± 0.5 mg/L (SC) during the entire study with continuously providing aeration. Alkalinity was observed 125.23 ± 22.58 to
Farming intensive fish requires a huge amount of good freshwater quality and discharges the wastewater to outside environment (Sauthier et al., 1998; De Stefani et al., 2011). Therefore, it is very much importance of aquaculture to reuse or recycle water as well as treat waste water and water before releasing to environment because water is a limited resource and discharge the untreated water from aquaculture can contribute to degrade our environment (Adler et al., 2000a, b). The study result showed that the total water exchanged during culture period in aquaponics systems was more than 70% more efficient than in normal culture: 475.2 L vs. 34,560 L (Table 2). Water loss in
spongy. 2.3. Statistical analyses All results were assessed for normality and expressed as mean value ± standard deviation by Excel 2016. Single classification ANOVA was used for comparison of the significant difference between the means of the treatments. The level of significance was set at P < 0.05. All statistical analyses and plot were performed using Origin Pro. version 9.1.
Table 1 Water quality parameters (mean values ± standard deviation) in two treatments snakehead in aquaponics (SAQ) and snakehead in normal farming-control experiment (SC) during the study period. Mean values accompanied by the same letter in the same row are not significantly different (P > 0.05). Parameter analyzed
Measure unit
SAQ
SC
Morning Temperature pH DO Alkalinity NH3 NO2
C u pH % (saturation) mg/L CaCO3 mg/L mg/L
Afternoon a
28.05 ± 0.67 6.99 ± 0.08a 4.92 ± 0.41a 125.23 ± 22.58a 0.010 ± 0.002a 0.28 ± 0.25a
Tolerance and Optimal range
Morning b
31.75 ± 0.76 7.77 ± 0.20b 6.93 ± 0.27b 156.88 ± 19.79b 0.030 ± 0.003b 0.58 ± 0.41b
5
Afternoon a
26.34 ± 1.03 7.16 ± 0.18a 3.46 ± 0.51c 106.56 ± 17.28c 0.05 ± 0,034c 0.56 ± 0.71b
33.47 ± 1.74b 7.95 ± 0.17b 5.50 ± 0.50d 116.38 ± 16.39d 0.16 ± 0,11d 2.59 ± 1.52c
28–32 6.5–9.0 > 3–5 50–300 0.2–2.0 < 1.0
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Table 2 Water exchange in two treatments over the experiment. Days
Percentage of water exchange (%) SAQ
30 60 90 120 150 Total
Volume of water exchange (L) SC
SAQ
SC
1
2
3
1
2
3
1
2
3
1
2
3
5 10 10 10 8 33
5 10 10 10 8 33
5 10 10 10 8 33
240 520 520 520 600 2400
240 520 520 520 600 2400
240 520 520 520 600 2400
72 144 144 144 115.2 475.2
72 144 144 144 115.2 475.2
72 144 144 144 115.2 475.2
3456 7488 7488 7488 8640 34,560
3456 7488 7488 7488 8640 34,560
3456 7488 7488 7488 8640 34,560
aquaponics systems is caused by evaporation, plant absorb, fish splashing and sludge removal. Normally, the water loss is ranging from ∼5 to 40% depending on the conditions (temperature, biofilter construction, greenhouse conditions, etc.) (Lennard and Leonard, 2005; Endut et al., 2014, 2016). 3.3. Aquaculture production The growth indicator of fish: body weight and length, survival rate and food conversation ratio (FCR) were shown in Table 3. The body weight and length growth of snakehead in the aquaponics system were much faster than those of snakehead in normal system. The results in Table 3 and Fig. 7 showed the weight gain of fish during the 150 days grow-out period, reaching 437.13 g vs. 215.68 g. and 32.63 cm vs. 27.34 cm in length. Based on the previous studies, the snakehead in normal farming in plastic pond after 150 days culturing was reaching 264 ± 40 to 357 ± 39.2 g (Lan et al., 2011; Phong, 2012). It was proved that after 150 days of farming, snakehead in aquaponics was growing faster than fish culturing in normal condition. Survival rate of fish in aquaponics was respectively higher than fish in normal system: 99.76% vs. 71.40%. The survival rate of snakehead in aquaponics met with the results of culturing snakehead in RAS (∼97.00–98.75%) (Van and Thich, 2014). The average survival rate of culturing snakehead in pond at density from 70 to 100 fish/m2 was ranging ∼60–70% after 150 days period (Nha, 2012; Phong, 2012). In industrial fish culture, feed is a main factor to grow fish. It accounted around 50% of cost. Feed conversion is described as the ability to convert the feed into biomass. The lower feed conversion means fewer feed needed to gain 1 kg biomass. The result showed that the feed conversation ratio (FCR) were 1.25 (SAQ) and 2.25 (SC) significantly difference. In normal farming condition, the FCR of snakehead was various from 1.5 to 4.0 (Muthmainnah, 2013; Amin et al., 2015; Farhana et al., 2016). When rearing snakehead in the aquaponics system, all the environmental factors was controlled to creating a stable environment to help fish grow and develop well. The maintaining optimal environmental indicators by the biological filter in the system was helping fish digest food better, reducing stress, less wasted food, increasing feed
Fig. 7. Weight growth curve of snakehead in applied aquaponics (SAQ) and normal culture system-control experiment (SC) for 150 days.
consumption. In addition, due to maintaining good water quality, it is possible to increase the stocking density, which will increase fish productivity, reduce farming area. This is a significant model applying and building the sustainable aquaculture and agriculture by ensuring and enhancing the quality of water and saving water in the farming process. 3.4. Agriculture production During 150 days of experiment, the average production of water spinach/bed in aquaponics systems (SAQ) was more than two times (406.4 vs. 188 kg) the average production of water spinach/bed in normal planting systems (VC) (Fig. 8a). The average yield of water spinach in aquaponics systems was higher to the one in normal cultivation respectively (2.1 vs. 1.0 kg/m2) (Table 4) (Fig. 8b). Water spinach is an herbaceous aquatic or semi-aquatic perennial plant in subtropical and tropical regions. The vegetable was grown well in water or on moist soil, therefore, it was growth faster and got higher yield in applied aquaponics systems. Moreover, in aquaponics, water spinach was watering with nutrients and water from the fishpond during cultivation period while water spinach in normal planting- control treatment just watering two times/day only.
Table 3 Growth performances of snakehead Channa striata (mean values ± standard deviation) were observed in two treatments SAQ: snakehead + water spinach in Aquaponics and SC: snakehead in normal farming- control experiment during the study period. Mean values accompanied by the same letter in the same row are not significantly different (P > 0.05). Parameter
SAQ
SC
Mean initial weight (g) Mean final weight (g) Mean initial length (cm) Mean final length (cm) Survival rate (%) Food conversation ratio
5.36 ± 1.46a 437.13 ± 36.48a 8.51 ± 1.04a 32.63 ± 3.33a 99.76 ± 0.55a 1.25 ± 0.05a
5.37 ± 1.63a 215.68 ± 32.10b 8.54 ± 1.04a 27.34 ± 3.15b 71.40 ± 7.98b 2.25 ± 0.07b
3.5. Evaluate the income in applied aquaponics and normal farming system After 150 days, the total income from snakehead and water spinach in aquaponics was 4 times higher than in normal farming systems: 1219.42 $US and 307.04 $US (Table 5) (Fig. 9a). The price of products in aquaponics was 150% higher than products in normal systems (Table 5): fish in aquaponics get the market size and the customers preferred the flesh and flavor of snakehead meat in aquaponics; the water spinach in aquaponics was younger, crispy and softer than water spinach in normal planting system. The initial net profit in aquaponics 6
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Fig. 8. (a) Total water spinach productions during 150 days of experiment in the two treatments (applied aquaponics (SAQ) and normal planting system- control experiment (VC); (b) Monthly average production of water spinach in the two treatments (applied aquaponics (SAQ) and normal planting system (VC).
investment; local fish – snakehead fish with high market rice. Besides, culturing snakehead in aquaponics builds up the green and ecological agriculture by saving more water and enhancing the quality and quantity of food production and adapting to climate change. It is saving more than 70% of water exchange than in ordinary aquaculture, improving good quality and quantity of water in pond as well as discharging. The product of snakehead in aquaponics more productive: higher survival ratio of fish: 99.76% vs. 71.40%; 3 times higher in fish yield: 366 kg vs. 130 kg. The productions of water spinach were more advantage in aquaponics systems: 406.4 kg vs. 188 kg. The total income from snakehead and water spinach in aquaponics was 4 times higher than in normal farming systems: 1219.42 $US and 307.04 $US. It was especially not using any chemical during cultivating period in aquaponics that produce the fresh and healthy food to consumers. Based on our present findings might have important implications towards to manage any further development of snakehead industry, as well as contribute to applied aquaponics systems to other high value local species. Besides, using cycled and reusable and utilizing local materials will keep the aquaponics lasting and expanding to social life, especially in developing countries which are the main bow supplying food to feed the world. Moreover, under climate changing, applied aquaponics is meaningful in draught prone, flood prone and coastal saline affected soil region to produce fish and vegetable round the year.
Table 4 The production of water spinach in applied aquaponics system (SAQ) and normal planting systems – control experiment (VC). Number of harvests
1 2 3 4 5 6 7 8 Total Average STDVE
Average production (kg) /m2
Average production (kg)/bed (24 m2)
SAQ
VC
SAQ
VC
1.6 1.8 1.9 2.2 2.2 2.3 2.5 2.4 16.9 2.1 0.29
1.3 0.6 1.0 0.8 1.0 0.9 1.3 0.9 7.8 1.0 0.23
39.2 44 45.6 52 53.6 56 59.2 56.8 406.4 50.8 7.08
31.2 15.2 24.8 19.2 23.2 21.6 31.2 21.6 188 23.5 5.54
was 633.86 $US vs (−16.46) $US (Fig. 9b). The percentage of net profit in applied aquaponics was 108.24% highly potential attracting farmers investment while the initial net profit in normal farming systems was (−5.09%) (Fig. 9c). The fish in aquaponics used feed more efficiency with FCR: 1.25 vs. 2.25 and higher in survival rate that were increasing net profit. Therefore, it is necessary applying aquaponics to cultivate snakehead to increase the income and friendly to environment.
Declaration of Competing Interest The authors declare that there are no competing interests regarding the publication of this paper.
4. Conclusion Farming intensive fish requires a huge amount of good freshwater quality and discharges the wastewater back to outside environment. This study shows that it is more advantage to utilize available local materials and local species in aquaponics: using locally available coconut peat as a base soil to reduce the soil-less culture in the heavily salted soil cultivation area; plastic floating pond saving more money for
Acknowledgements The present study was supported by Saphenix Co., Ltd., Tra Vinh province, Vietnam; Tra Vinh University, Vietnam and Da–Yeh University, Taiwan.
Table 5 Income from snakehead and water spinach in two systems ($US). Products
Snakehead Water spinach Sum Initial investment cost (Instruction, electrical cost) Net profit
Applied aquaponics
Normal farming systems
Amount (kg)
Price ($US/kg)
Total ($US)
Amount (kg)
Price ($US/kg)
Total ($US)
366 406.4
2.61 0.65
955.26 264.16 1219.42 585.56 633.86
130 188
1.74 0.43
226.20 80.84 307.04 323.50 −16.46
The price of the products was the current price of the market in Vietnam for safe products. This was the real price that the farm was selling to the market. 7
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Fig. 9. (a) The income in (SAQ) and normal farming systems - control experiment (SC + VC). (b) The ratio between initial investment cost and net profit (c) Net profit in applied aquaponics and normal farming system.
Appendix A. Supplementary data
FAO (Food and Agriculture Organization of the United Nations), 2019. Fisheries and Aquaculture Department. Species Fact sheet. Channa striata (Bloch, 1973). http:// www.fao.org/fishery/species/3062/en. Farhana, T., Hasan, M.E., Mamun, A.A., Islam, M.S., 2016. Commercially culture potentiality of striped snakehead fish Channa striatus (Bloch, 1793) in earthen ponds of Bangladesh. Int. J. Pure Appl. Zool. 4 (2), 168–173. Available online: http://www. alliedacademies.org/articles/commercially-culture-potentiality-of-stripedsnakehead-fish-channa-striatus-bloch-1793-in-earthen-ponds-of-bangladesh.pdf. Hasan, N.B.A., 2014. Aquaponics System for Treat a Catfish Wastewater. Available online:. Thesis graduated from University – Faculty of Civil Engineering and Earth Resources – University Malaysia Pahang. http://umpir.ump.edu.my/id/eprint/ 9306/1/NURAIN%20BINTI%20ABU%20HASAN.PDF. Lan, L.M., Nguyen, T.H., Duong, N.L., 2011. Nuôi cá lóc (Channa sp.) trong bể lót bạt tại tỉnh Hậu Giang. In: Proceedings of the 4th Conference on Fisheries Science. Can Tho University. pp. 395–404. (In Vietnamese). Available online: http://www.vietlinh.vn/ nuoi-trong-thuy-san/ca-loc-lot-bat.pdf. Lennard, W.A., Leonard, B.V., 2005. A comparison of reciprocating flow versus constant flow in an integrated, gravel bed, aquaponic test system. Aquac. Int. 12 (6), 539–553. https://doi.org/10.1007/s10499-005-8528-x. Long, D.N., 2010. Textbook of Freshwater Aquaculture Technique: Bookcase of Can Tho University. Can Tho University (In Vietnamese). Mamat, N.Z., Shaari, M.I., Wahab, N.A.A.A., 2016. The production of catfish and vegetables in an aquaponic system. Fish. Aquacult. J. 7 (4), 1–3. https://doi.org/10.4172/ 2150-3508.1000181. Muthmainnah, D., 2013. Grow out of striped snakehead (Channa striata) in swamp water system using fences and cages. In: 4th International Conference on Biology, Environment and Chemistry IPCBEE. IACSIT Press, Singapore 58. pp. 52–55. Available online: https://pdfs.semanticscholar.org/a341/ e40a8a5b37dcbda0e1b15aead7400c83bf80.pdf. Nguyen, V.H., Tuyet-Hanh, T.T., Unger, F., Dang-Xuan, S., Grace, D., 2017. Food safety in Vietnam: where we are at and what we can learn from international experiences. Infect. Dis. Poverty 6 (1), 39. https://doi.org/10.1186/s40249-017-0249-7. Nha, N.V., 2012. Thực nghiệm nuôi cá lóc (Channa sp.) trong bể lót bạt ở xã Ninh Quới, huyện Hồng Dân, tỉnh Bạc Liêu. Thesis graduated from University – Department of Fisheries – Can Tho University (In Vietnamese). Petrea, S.M., Cristea, V., Dediu, L., Contoman, M., Lupoae, P., Mocanu, M., Coada, M.T., 2013. Vegetable production in an integrated aquaponic system with rainbow trout and spinach. Bull. UASVM Anim. Sci. Biotechnol. 70 (1), 45–54. https://doi.org/10. 15835/buasvmcn-asb:70:1:9485. Pham, V.H., Arthur, P.J., Oosterveer, M.P., van den Brink, P.L., Pham, T.M.H., 2016. Pesticide use in Vietnamese vegetable production: a 10-year study. Int. J. Agric. Sustainability 14 (3), 325–338. https://doi.org/10.1080/14735903.2015.1134395. Phong, N.B., 2012. Thực nghiệm nuôi cá lóc đen (Channa striata) trong bể bạt tại tỉnh Bạc Liêu. Thesis graduated from University – Department of Fisheries – Can Tho University (In Vietnamese). Rakocy, J., Masser, M., Losordo, T., 2006. Recirculating Aquaculture Tank Production Systems: Aquaponics – Integrating Fish and Plant Culture. SRAC Publication No.
Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.aquaeng.2020. 102057. References Adler, P.R., Harper, J.K., Wade, E.W., Takeda, F., Summerfelt, S.T., 2000a. Economic 307 analysis of an aquaponic system for the integrated production of rainbow trout and 308 plants. Int. J. Recirc. Aquacult. 1 (1), 15–34. https://doi.org/10.21061/ijra.v1i1. 1359. Adler, P.R., Harper, J.K., Takeda, F., Wade, E.M., Summerfelt, S.T., 2000b. Economic evaluation of hydroponics and other treatment options for phosphorus removal in aquaculture effluent. Hort Sci. 35 (6), 993–999. https://doi.org/10.21273/HORTSCI. 35.6.993. Amin, S.M.N., Muntaziana, M.P.A., Kamarudin, M.S., Rahim, A.A., Rahman, M.A., 2015. Effect of different stocking densities on growth and production performances of chevron snakehead Channa striata in fiberglass tanks. North Am. J. Aquacult. 77, 289–294. https://doi.org/10.1080/15222055.2015.1024361. Boyd, C.E., 1990a. Water Quality in Ponds for Aquaculture. Alabama Agricultural Experiment Station, Auburn University, Auburn, Alabama p. 482. Boyd, C.E., 1990b. Water Quality Management for Pond Fish Culture. Department of Fisheries and Allied Aquaculture. Agricultural Experiment Station, Auburn, Alabama, Birmingham Publishing Company, New York. Chung, D.M., Sinh, L.X., 2011. An analysis of snakehead value chain (Channa striata.) cultured in the Mekong Delta. In: The National Conference Proceedings on Aquaculture and Fisheries. Can Tho University 4. pp. 512–523. Da Rocha, A.F., Filho, M.L.B., Stech, M.R., da Silva, R.P., 2017. Lettuce production in aquaponic and bio floc systems with silver catfish Rhamdia quelen. Bol. Inst. Pesca. 44, 64–73. https://doi.org/10.20950/1678-2305.2017.64.73. De Koning, J.I.J.C., Crul, M.R.M., Wever, R., Brezet, J.C., 2015. Sustainable consumption in Vietnam: an explorative study among the urban middle class. Int. J. Consum. Stud. 39, 608–618. https://doi.org/10.1111/ijcs.12235. De Stefani, G., Tocchetto, D., Salvato, M., Borin, M., 2011. Performance of a floating treatment wetland for in-stream water amelioration in NE Italy. Hydrobiologia 674 (1), 157–167. https://doi.org/10.1007/s10750-011-0730-4. Endut, A., Jusoh, A., Ali, N., 2014. Nitrogen budget and effluent nitrogen components in aquaponics recirculation system. Desalin. Water Treat. 52 (4–6), 744–752. https:// doi.org/10.1080/19443994.2013.826336. Endut, A., Lananan, F., Abdul Hamid, S.H., Jusoh, A., Wan Nik, W.N., 2016. Balancing of nutrient uptake by water spinach (Ipomoea aquatica) and mustard green (Brassica juncea) with nutrient production by African catfish (Clarias gariepinus) in scaling aquaponic recirculation system. Desalin. Water Treat. 57 (60), 29531–29540. https://doi.org/10.1080/19443994.2016.1184593.
8
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Truong, T.T., Yap, M.H.T., Ineson, E.M., 2012. Potential Vietnamese consumers’ perceptions of organic foods. Br. Food J. Hyg. Rev. 114 (4), 529–543. https://doi.org/ 10.1108/00070701211219540. Van, P.T.T., Thich, C.V., 2014. Ảnh hưởng số lần cho ăn lên tốc độ tăng trưởng của cá lóc (Channa striata) nuôi trong hệ thống tuần hoàn. AGU J. Sc. 4, 79–84. Available online: http://www.agu.edu.vn:8080/bitstream/AGU_Library/2618/1/Bai%2014-phan %20Thi%20Thanh%20Van%20va%20Cao%20Van%20Thich.pdf. (In Vietnamese). Vietnam Ministry of Health, 2016. Joint Annual Health Review 2015 Strengthening Primary Health Care at the Grassroots Towards Universal Health Coverage. Available online:. Medical Publishing House. http://jahr.org.vn/downloads/ JAHR2015/JAHR2015_full_EN.pdf. Wahab, S.Z.A., Kadir, A.A., Hussain, N.H.N., Omar, J., Yunus, R., Baie, S., 2015. The effect of Channa striatus (Haruan) extract on pain and wound healing of post-lower segment caesarean section women. Evid. Based Complement. Altern. Med. 6. https:// doi.org/10.1155/2015/849647. Walter, R., Courtenay Jr., , Williams, J.D., 2004. Snakeheads (Pisces, Channidae) – A Biological Synopsis and Risk Assessment. U.S. Geological Survey Circular 1251. Available online:. https://nas.er.usgs.gov/taxgroup/fish/docs/ SnakeheadRiskAssessment.pdf.
454. Available online:. Southern Regional Aquaculture Center. http://www. gemstone.umd.edu/team-sites/classof2014/mega/documents/Rakocy_RAS.PDF. Sahid, N.A., Hayati, F., Rao, C.V., Ramely, R., Sani, I., Dzulkarnaen, A., Zakaria, Z., Hassan, S., Zahari, A., Ali, A.A., 2018. Snakehead consumption enhances wound healing? From tradition to modern clinical practice: a prospective randomized controlled trial. Evid. Complement. Alternat. Med. 9. https://doi.org/10.1155/2018/ 3032790. Sauthier, N., Grasmick, A., Blancheton, J.P., 1998. Biological denitrification applied to a marine closed aquaculture system. Water Res. 32 (6), 1932–1938. https://doi.org/ 10.1016/S0043-1354(97)00406-5. Simmons, L., Scott, S., 2007. Health concerns drive safe vegetable production in Vietnam. Leisa Mag. 23 (3), 22–23. Available online: http://lib.icimod.org/record/12722/ files/3548.pdf. Sinh, L.X., Navy, H., Pomeroy, R., 2014. Value chain analysis of snakehead fish in the lower Mekong Basin of Cambodia and Vietnam. Aquacult. Econ. Manage. 18 (1), 76–96. https://doi.org/10.1080/13657305.2014.855956. Tra Vinh Department of Natural Resource and Environment, 2018. Annual Report. Tra Vinh GSO (General Statistics Office), 2019. Available online: http:// thongketravinh.vn/.
9
Contents lists available at ScienceDirect
Aquacultural Engineering journal homepage: www.elsevier.com/locate/aque
Productivity and economic viability of snakehead Channa striata culture using an aquaponics approach
T
Tran Thi Ngoc Bicha,c, Doan Quang Trib,*, Chen Yi-Chinga, Huynh Dang Khoac a
Environmental Engineering Department, Da-Yeh University, Changhua, Taiwan Sustainable Management of Natural Resources and Environment Research Group, Faculty of Environment and Labour Safety, Ton Duc Thang University, Ho Chi Minh, Viet Nam c Tra Vinh University, Tra Vinh, Viet Nam b
A R T I C LE I N FO
A B S T R A C T
Keywords: Green agriculture Applied aquaponics Snakehead Water spinach Climate change
This study was carried out to investigate the viability of utilizing aquaponic technology in culturing local fish: snakehead Channa striata and water spinach Ipomoea aquatica. Snakehead was raised for 150 days in a floating plastic pond with an area of 3 × 4 × 1.2 m having a capacity volume of ∼14.4 m3. Fish were randomly arranged into two experimental systems at density of ∼0.3 kg fingerlings/m3 e.g. SAQ – snakehead in aquaponics; SC – snakehead in normal system where control ponds were continuously aerated with ∼20% daily exchange of water. Fish were fed commercial feed twice a day. Initial results showed that in aquaponics compared with normal systems the SAQ efficiency exhibited 70% water exchange; five times lower in NH3 level: (0.01–0.03 mg/ L vs. 0.05–0.16 mg/L); three times lower in NO2 level: (0.28–0.58 mg/L vs. 0.56–2.59 mg/L). Snakehead production was significantly higher in aquaponics with higher survival ratio of fish: 99.76% vs. 71.40%; ∼3 times higher in fish yield: 366 kg vs. 130 kg. The production of water spinach was also elevated in aquaponics versus normal systems 406.4 kg vs. 188 kg. The total income from snakehead and water spinach in SAQ were 4 times higher than in normal farming systems: 1219.42 $US and 307.04 $US. Based on the results of the current study, it is expected that applying aquaponics utilizing local available materials and species will enhance the sustainability of the overall system and keep the aquaponics lasting and expanding to social life especially on sustainable culturing snakehead Channa striata.
1. Introduction In Asia countries, snakehead Channa striata is a popular carnivorous freshwater fish with high value in the market because of the firm, white and boneless tasty flesh and flavor (Walter et al., 2004; Sinh et al., 2014) and the uses of fish for medicinal purposes (Sahid et al., 2018; Wahab et al., 2015). Cultured snakehead has become an economically important freshwater fish in developing countries as Thailand, Malaysia, Indonesia, Bangladesh, India and Vietnam. In 2016, the total global capture and aquaculture production of snakehead Channa striata reached 92,523 t (FAO, 2019). In Vietnam, snakehead has been cultured for 60 years and becomes an important species in Mekong Delta. The production of snakehead in Vietnamese Mekong Delta increased from 5300 to 40,000 t (2002–2009) (Chung and Sinh, 2011). An Giang, Dong Thap, Hau Giang, Vinh Long, and Tra Vinh are provinces dominating of culturing snakehead (Long, 2010). In Tra Vinh province, the area of farming snakehead has been continuously increasing and
⁎
reaching 30,000 t in 2018. In 10 years, the area of farming snakehead has expanded from 61 ha to 270 ha (2010–2018) (Tra Vinh GSO, 2019). Intensive culture of snakehead has resulted in increased feed and chemical input into natural water bodies that negatively affects water quality. The traditional farming systems of snakeheads have mainly used live feed or industrial feed with high protein ratio (∼30%–40%). Almost the waste from intensive snakehead ponds directly drain to the environment causing serious environmental pollution and the depletion of natural aquatic resources in freshwater. Furthermore, according to a report by Tra Vinh Department of Natural Resource and Environment, 2018, most of intensive cultured snakehead has been using groundwater to supply water source to ponds that cause depletion of freshwater resources. Additionally, combined with climate change, the salinization and pollution of watercourses and bodies, and the increased degradation of water-related ecosystems, freshwater scarcity is growing critically. Moreover, food security is recognized as most concerning issue
Corresponding author. E-mail address: [email protected] (D.Q. Tri).
https://doi.org/10.1016/j.aquaeng.2020.102057 Received 26 June 2019; Received in revised form 16 October 2019; Accepted 15 January 2020 Available online 24 January 2020 0144-8609/ © 2020 Elsevier B.V. All rights reserved.
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
and adapting to climate change in the future.
related to population growth. To increase food demand, as other developing countries, Vietnam has promoted the use of pesticides to increase the yield of agricultural products, especially in vegetables (Pham et al., 2016). Recently, announcements on food poisoning by unsafe vegetables have been exposed and widely broadcast in media in Vietnam. Eating foods contaminated with pesticides or other chemicals had increased the cause of cancer e.g., 125 000 new cases of cancers (2012) (140 cases per 100 000 population) and predicted to increase to 190 000 new cases by 2020, when 75 000 deaths will result from cancers per year (84 deaths per 100 000 population) (Nguyen et al., 2017). The Vietnam Ministry of Health, 2016 reported that there were 677 incidents of food poisoning that affected more than 21,000 people (2011–2014). Therefore, to demand for healthy and environmentally friendly food, many Vietnamese consumers willing to pay more for organic or safe food (Simmons and Scott, 2007; Truong et al., 2012; De Koning et al., 2015) Aquaponics could play in producing healthy and sustainable food. Aquaponics now is considered as a sustainable fishery/agricultural model in terms of enhancing the productivity by allowing the sustainable growth of two crops in one system. Aquaponics is a combination of aquaculture and plant cultivation to enhance productivity through the achievement of the symbiotic interaction in reducing the need of chemical fertilizer for plant and the discharged water (Rakocy et al., 2006). Safe and friendly to environment: the mechanical process of the model is based on a circulating biological filtration rules: wastewater from aquariums (containing wastewater) is fed to vegetables. The vegetable bed acts as a circulating biological filtration system: they absorb waste from the aquarium and supplies clean water return to the fish tank. There are numerous researches focusing on aquaponics techniques; type of aquaponics; The comparison on the economics, environmental and social benefits of aquaponics. Lacking in the literature is a study focusing on utilize local materials as well as local species to aquaponics system to reduce investment cost to increase the income, especially using snakehead Channa striata in aquaponics. Moreover, there has been little focus on how to apply aquaponics in developing countries with low – income where is organic food/safe food still very expensive and impossible to build it in rural area or urban cities. Besides, to supply enough food to human requirement, intensive aquaculture systems are developing rapidly, and most located in developing countries where the major crisis with climate change, pollution and water depletion are felt. Normally, tilapia is the most popular species to culture in aquaponics systems. Recent efforts by researches have focused on replacing tilapia with other aquatic species with high market value such as Catfish (Hasan, 2014); Trout (Petrea et al., 2013); African Catfish (Mamat et al., 2016); Silver catfish (Da Rocha et al., 2017). However, little work has been conducted in Vietnam or globally to apply and promote the rearing and culture techniques of snakehead in aquaponics combining with utilize available local materials as coconut peat, rice husk, water hyacinth roots, bamboo tree, Styrofoam, canvas, etc., to reduce investment cost to increase the potential income to local farmers. Therefore, it is a need to conduct a study covering all the aspects of snakehead fish industry by applying aquaponics to build green agriculture and improve quality and quantity of food production. The purpose of the study is culturing high market value fish snakehead Channa striata in aquaponics to increase the productivity and profits to farmers. The most importance of applied aquaponics is ultimately reused and recycled local materials to reduce initial investment cost and culture local high value species to increase the potential profits that strongly attract farmers investment. The results of this study will be potential to enhance the quality and quantity of industrial farming snakehead not only in Vietnam but also productive to other countries developing in commercially culturing snakehead. Furthermore, the conducted results of our study potentially contribute to develop new and local design of aquaponics suitable to culture high value local species to keep the aquaponics lasting and expanding to social life to saving more water and improving food production to feed the world
2. Methodology Our experiment design was based on the local conditions and the future sustainable farming systems to build up the new farming system more adapted to climate changing and increase the quality and quantity of food source. We collected the data from GSO Tra Vinh and went to the field to do the survey on the current situation of locally culturing snakehead, local materials, the policy and potential to develop intensive system but sustain and friendly to environment. Our purpose was primarily designed and explored the potential of apply aquaponics to culture snakehead industrially. Further, we also desired to apply aquaponics at low – income area to develop the low cost and friendly farming systems to improve food security and food production. 2.1. Study area Tra Vinh province which is belonging to Vietnamese Mekong Delta is coastal area strongly developing in intensive aquaculture. In Tra Vinh province, the area of farming snakehead has sharply increased in recent years. In 10 years (2010–2018), the area of farming snakehead is expanded to 5 times from 61 ha to 270 ha. Normally, snakehead is intensively cultured in ponds by farmers who utilize daily exchanges of water and use significant amounts of chemicals to prevent and treat the disease. This farming method has caused serious negative impact to water resources and polluted the environment. Moreover, Tra Vinh province is one of coastal provinces of the Vietnamese Mekong Delta where agricultural water demand is an extreme issue due to sea level rise that affects most on freshwater intensive culture. Some areas have been seriously affected by sea level rise and salted the soil. In Vietnamese Mekong Delta and other Asia countries, there are abundant sources of coconut husk, rice husk and other agricultural materials can replace the base soil in developing the agriculture. Therefore, it is necessary to apply aquaponics to culturing snakehead combining with utilize available local materials in newly design aquaponics systems to keep the systems more friendly to environment and advantage in productivity and economic viability. The study was conducted in an aquaponics farm of Saphenix Co., Ltd. at Luong Hoa village, Chau Thanh district, Tra Vinh province, Vietnam for a period of 150 days: 02/10/2018 – 07/15/2018. The systems were designed in the net house with 6 floating plastic ponds (3 × 4 m) and 6 vegetable beds (8 × 3 m) (Figs. 1 and 2). The arrows in Fig. 1 showed the flow of water. Water flowed from fishpond to filter tank to vegetable bed. Then, water run thoroughly from the top of the vegetable bed and returned clean water to fishponds via the drainage system at the end of the vegetable bed. 2.2. Experimental design 2.2.1. Aquaculture Fingerlings of snakehead (Fig. 3) were collected from hatchery in Dong Thap province, Vietnam with averaged weight 5.36 ± 1.54 SD g and length 8.53 ± 1.04 SD cm. Before stocking, fish were disinfected by bath treatment of 5 ppm KMnO4. Snakehead was cultured in floating plastic ponds with an area of 3 × 4 m and water level 1.2 m depth having a capacity of 1440 L. Each pond had inlet and outlet facilities connected to the bio- filter system locating along the side of the system. The bio-filter tanks were design with layers from the top to the bottom of filter tank: gravel 4 × 6, gravel 1 × 2, sand and cap of water bottle mixing with pieces of cutting net. Each layer was put in a net bag that could easy to arrange, wash and exchange. For fingerlings stocking, firstly, we scaled one kilogram of fingerlings with triplication. Secondly, we counted number of fingerlings per kilograms. Then, fish were randomly arranged into two experimental systems at stocking density of ∼0.3 kg fingerlings/m3 (70 fish/m2) SAQ – snakehead in aquaponics; 2
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Fig. 1. The layout of the experimental design (SAQ snakehead in applied aquaponics; SC was snakehead cultured in ordinary system as the control pond; VC presented water spinach growing in ordinary condition as the control experiment).
SC – snakehead in control ponds following the normal or traditional snakehead culture which were continuously aerated with about 20% daily exchange of water. In normal culture systems, water in pond is exchanging daily at least 20%: pumping water in pond out to environment without treatment and then add the same amount of soaking out back to the pond. Each treatment had three assigned replications. Data for all water exchange events were recorded. During the study period surface water from river was the main source of water to the aquaria. The water from river was pumped to the supplying water pond and treated with 5 ppm KMnO4 before adding to the cultivating systems. Aeration pump was used to maintain adequate level of dissolved oxygen ∼4 mg/L. Fish were fed commercial feed at the average ratio at 5% of fish body weight. The fish were manually fed twice a day (07:00 am and 05:00 pm) with a commercial compound feed in the form of extruded pellets (Viet Thang feed, Vietnam; composition: 40% crude protein, 6% crude fat; 5% crude fiber, 16% ash, 2.5% NaCl, 2.5%
calcium, and 1% calcium/phosphorus, as-fed basis). Fish were fed 6 days continuously and then took one day without feeding to promote food digestion more efficiency. The lengths and weights of 50 live fish/ pond were recorded one time/month during the culture period. After 150 days, all fish were harvested by the market size (Fig. 4). The growth performances of snakehead Channa striata was calculated using formula (1), (2), (3) and (4).
Survival rate (Pauly 1980) =
No. of total fry obtained × 100 No. of total fry stocked
Length gain = Final body length (cm) − Initial body length (cm)
(1)
(2)
Weight gain (g) = Final body weight (g) − Initial body weight (g) (3)
Fig. 2. (a) Applied aquaponics experiments; (b) Automatic water pumping systems; (c) Illustrated vegetable bed; (d) Floating plastic pond; (e) Water from vegetable bed returning fresh and clean water back to the fish tank; (f) Water spinach grow well in applied aquaponics. 3
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Fig. 3. Snakehead fingerlings.
Fig. 4. Snakehead got the market size 400−500 g/fish after 150 days of culturing.
FCR (Castell and Tiews 1980) =
Total feed used (kg ) Final body wt (kg ) − Initial body wt (kg ) (4)
Water quality parameters temperature and pH were tested twice daily in the morning (07:00–08:00 am) and in the afternoon (14:00–15:00 pm) with the help of pH meter pen type AZ 8685 (Taiwan). Other water quality parameters: O2, NO2, NH3, Alkalinity were recorded 1 time per week throughout the culture period by Sera test kit (German), LAQUAact DO110 (Japan), Hanna Checker Colorimeters. 2.2.2. Agriculture The applied aquaponics was constructed by using available local materials to reduce the investment cost as well as increasing the profits to local farmers. Six round 24 m2 (8 × 3 m) plastic bed were prepared for growing water spinach Ipomoea aquatic (Fig. 2a). Vegetable bed was designed by reusing the Styrofoam which was containers of baby shrimp. The frames of vegetable bed were strongly holding by bamboo trees which was very cheap and grown at farmer’ garden. The vegetable bed (Fig. 2c) was designed many layers as a filter system from bottom to the top the first layer: gravel 4 × 6 cm; the second layer: gravel 1 × 2 cm and the third layer: coconut peat. Each layer was separated by HDPE net 64 mesh (200 holes/cm2). Coconut peat was used as the base soil to grow water spinach. The seedlings were placed into the holes: three seeds per hole. The space between each hole was 4–6 cm (Fig. 5). Water is automatically timing pumping 6–10 times/day (3–8 h/day) depending on the growth of fish and plants. In ordinary planting system, water spinach was watering two times per day. Fertilizers is used for every 10–15 days. Some chemicals as Aztron, Dithane 80WP, Sumicidin 10EC are used to treat the worms. However, in this
Fig. 5. Water spinach in normal farming system. Coconut peat was used as a based soil to grow water spinach. The seedlings were placed into the holes: three seeds per hole. The space between each hole was 4−6 cm.
experiment, the normal planting systems which acted as control system, watering was done as normal twice a day at 8:00 am and 4:00 pm until water drained from the bottom of the raised beds. Fertilizers and chemicals were not used in the planting control systems. The experiment was triplicated. Plant growth parameters measured were final biomass. Experimental time was recorded as number of days after sowing (DAS). At 24 DAS all the plants ranging from 35 to 45 cm (Fig. 6) in height were cut at ground level and above ground biomass measured. After next 10 days, we harvested another round of water spinach. All the harvested water spinach was raw weight. Then, we raked and turned up the coconut peat and added some more coconut peat to keep them
4
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Fig. 6. Water spinach were cut at ground level at 24 DAS all the plants ranging from 35 to 45 cm in height.
3. Results and discussion
156.88 ± 19.79 mg/L CaCO3 (SAQ) and 106.56 ± 17.28 to 116.38 ± 16.39 mg/L CaCO3 (SC). During the experiment the ammonia value (NH3) varied from 0.01 ± 0.002 to 0.03 ± 0.003 mg/L (SAQ) and 0.05 ± 0.034 to 0.16 ± 0.11 mg/L (SC). The values of Nitrite (NO2) values were recorded in the spread of 0.28 ± 0.25 to 0.58 ± 0.41 mg/L (SAQ) and 0.56 ± 0.71 to 2.59 ± 1.52 mg/L (SC). All the physical and chemical parameters of the rearing water were found to be in the optimum range required for aquaculture practice in the freshwater aquaculture by Boyd (1990a,b) except the value of Nitrite in treatment experiment (SC) starting from the second month of farming period: nitrite concentration > 1.0 mg/L, especially in the afternoon.
3.1. Water quality and parameters
3.2. Water efficiency
All water parameters were within tolerable limits except the value of Nitrite in control treatment (SC). Table 1 showed the results of water quality parameters in two treatments during the study period (mean values ± standard deviation). The water temperature was recorded from 28.05 ± 0.67 to 31.75 ± 0.76 °C (SAQ) and 26.34 ± 1.03 to 33.47 ± 1.74 °C (SC). The pH ranged from 6.9 ± 0.1 to 7.8 ± 0.2 (SAQ) and 7.2 ± 0.2 to 8.0 ± 0.2 (SC). The dissolved oxygen was found 4.9 ± 0.4 to 6.9 ± 0.3 mg/L (SAQ) and 3.5 ± 0.5 to 5.5 ± 0.5 mg/L (SC) during the entire study with continuously providing aeration. Alkalinity was observed 125.23 ± 22.58 to
Farming intensive fish requires a huge amount of good freshwater quality and discharges the wastewater to outside environment (Sauthier et al., 1998; De Stefani et al., 2011). Therefore, it is very much importance of aquaculture to reuse or recycle water as well as treat waste water and water before releasing to environment because water is a limited resource and discharge the untreated water from aquaculture can contribute to degrade our environment (Adler et al., 2000a, b). The study result showed that the total water exchanged during culture period in aquaponics systems was more than 70% more efficient than in normal culture: 475.2 L vs. 34,560 L (Table 2). Water loss in
spongy. 2.3. Statistical analyses All results were assessed for normality and expressed as mean value ± standard deviation by Excel 2016. Single classification ANOVA was used for comparison of the significant difference between the means of the treatments. The level of significance was set at P < 0.05. All statistical analyses and plot were performed using Origin Pro. version 9.1.
Table 1 Water quality parameters (mean values ± standard deviation) in two treatments snakehead in aquaponics (SAQ) and snakehead in normal farming-control experiment (SC) during the study period. Mean values accompanied by the same letter in the same row are not significantly different (P > 0.05). Parameter analyzed
Measure unit
SAQ
SC
Morning Temperature pH DO Alkalinity NH3 NO2
C u pH % (saturation) mg/L CaCO3 mg/L mg/L
Afternoon a
28.05 ± 0.67 6.99 ± 0.08a 4.92 ± 0.41a 125.23 ± 22.58a 0.010 ± 0.002a 0.28 ± 0.25a
Tolerance and Optimal range
Morning b
31.75 ± 0.76 7.77 ± 0.20b 6.93 ± 0.27b 156.88 ± 19.79b 0.030 ± 0.003b 0.58 ± 0.41b
5
Afternoon a
26.34 ± 1.03 7.16 ± 0.18a 3.46 ± 0.51c 106.56 ± 17.28c 0.05 ± 0,034c 0.56 ± 0.71b
33.47 ± 1.74b 7.95 ± 0.17b 5.50 ± 0.50d 116.38 ± 16.39d 0.16 ± 0,11d 2.59 ± 1.52c
28–32 6.5–9.0 > 3–5 50–300 0.2–2.0 < 1.0
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Table 2 Water exchange in two treatments over the experiment. Days
Percentage of water exchange (%) SAQ
30 60 90 120 150 Total
Volume of water exchange (L) SC
SAQ
SC
1
2
3
1
2
3
1
2
3
1
2
3
5 10 10 10 8 33
5 10 10 10 8 33
5 10 10 10 8 33
240 520 520 520 600 2400
240 520 520 520 600 2400
240 520 520 520 600 2400
72 144 144 144 115.2 475.2
72 144 144 144 115.2 475.2
72 144 144 144 115.2 475.2
3456 7488 7488 7488 8640 34,560
3456 7488 7488 7488 8640 34,560
3456 7488 7488 7488 8640 34,560
aquaponics systems is caused by evaporation, plant absorb, fish splashing and sludge removal. Normally, the water loss is ranging from ∼5 to 40% depending on the conditions (temperature, biofilter construction, greenhouse conditions, etc.) (Lennard and Leonard, 2005; Endut et al., 2014, 2016). 3.3. Aquaculture production The growth indicator of fish: body weight and length, survival rate and food conversation ratio (FCR) were shown in Table 3. The body weight and length growth of snakehead in the aquaponics system were much faster than those of snakehead in normal system. The results in Table 3 and Fig. 7 showed the weight gain of fish during the 150 days grow-out period, reaching 437.13 g vs. 215.68 g. and 32.63 cm vs. 27.34 cm in length. Based on the previous studies, the snakehead in normal farming in plastic pond after 150 days culturing was reaching 264 ± 40 to 357 ± 39.2 g (Lan et al., 2011; Phong, 2012). It was proved that after 150 days of farming, snakehead in aquaponics was growing faster than fish culturing in normal condition. Survival rate of fish in aquaponics was respectively higher than fish in normal system: 99.76% vs. 71.40%. The survival rate of snakehead in aquaponics met with the results of culturing snakehead in RAS (∼97.00–98.75%) (Van and Thich, 2014). The average survival rate of culturing snakehead in pond at density from 70 to 100 fish/m2 was ranging ∼60–70% after 150 days period (Nha, 2012; Phong, 2012). In industrial fish culture, feed is a main factor to grow fish. It accounted around 50% of cost. Feed conversion is described as the ability to convert the feed into biomass. The lower feed conversion means fewer feed needed to gain 1 kg biomass. The result showed that the feed conversation ratio (FCR) were 1.25 (SAQ) and 2.25 (SC) significantly difference. In normal farming condition, the FCR of snakehead was various from 1.5 to 4.0 (Muthmainnah, 2013; Amin et al., 2015; Farhana et al., 2016). When rearing snakehead in the aquaponics system, all the environmental factors was controlled to creating a stable environment to help fish grow and develop well. The maintaining optimal environmental indicators by the biological filter in the system was helping fish digest food better, reducing stress, less wasted food, increasing feed
Fig. 7. Weight growth curve of snakehead in applied aquaponics (SAQ) and normal culture system-control experiment (SC) for 150 days.
consumption. In addition, due to maintaining good water quality, it is possible to increase the stocking density, which will increase fish productivity, reduce farming area. This is a significant model applying and building the sustainable aquaculture and agriculture by ensuring and enhancing the quality of water and saving water in the farming process. 3.4. Agriculture production During 150 days of experiment, the average production of water spinach/bed in aquaponics systems (SAQ) was more than two times (406.4 vs. 188 kg) the average production of water spinach/bed in normal planting systems (VC) (Fig. 8a). The average yield of water spinach in aquaponics systems was higher to the one in normal cultivation respectively (2.1 vs. 1.0 kg/m2) (Table 4) (Fig. 8b). Water spinach is an herbaceous aquatic or semi-aquatic perennial plant in subtropical and tropical regions. The vegetable was grown well in water or on moist soil, therefore, it was growth faster and got higher yield in applied aquaponics systems. Moreover, in aquaponics, water spinach was watering with nutrients and water from the fishpond during cultivation period while water spinach in normal planting- control treatment just watering two times/day only.
Table 3 Growth performances of snakehead Channa striata (mean values ± standard deviation) were observed in two treatments SAQ: snakehead + water spinach in Aquaponics and SC: snakehead in normal farming- control experiment during the study period. Mean values accompanied by the same letter in the same row are not significantly different (P > 0.05). Parameter
SAQ
SC
Mean initial weight (g) Mean final weight (g) Mean initial length (cm) Mean final length (cm) Survival rate (%) Food conversation ratio
5.36 ± 1.46a 437.13 ± 36.48a 8.51 ± 1.04a 32.63 ± 3.33a 99.76 ± 0.55a 1.25 ± 0.05a
5.37 ± 1.63a 215.68 ± 32.10b 8.54 ± 1.04a 27.34 ± 3.15b 71.40 ± 7.98b 2.25 ± 0.07b
3.5. Evaluate the income in applied aquaponics and normal farming system After 150 days, the total income from snakehead and water spinach in aquaponics was 4 times higher than in normal farming systems: 1219.42 $US and 307.04 $US (Table 5) (Fig. 9a). The price of products in aquaponics was 150% higher than products in normal systems (Table 5): fish in aquaponics get the market size and the customers preferred the flesh and flavor of snakehead meat in aquaponics; the water spinach in aquaponics was younger, crispy and softer than water spinach in normal planting system. The initial net profit in aquaponics 6
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Fig. 8. (a) Total water spinach productions during 150 days of experiment in the two treatments (applied aquaponics (SAQ) and normal planting system- control experiment (VC); (b) Monthly average production of water spinach in the two treatments (applied aquaponics (SAQ) and normal planting system (VC).
investment; local fish – snakehead fish with high market rice. Besides, culturing snakehead in aquaponics builds up the green and ecological agriculture by saving more water and enhancing the quality and quantity of food production and adapting to climate change. It is saving more than 70% of water exchange than in ordinary aquaculture, improving good quality and quantity of water in pond as well as discharging. The product of snakehead in aquaponics more productive: higher survival ratio of fish: 99.76% vs. 71.40%; 3 times higher in fish yield: 366 kg vs. 130 kg. The productions of water spinach were more advantage in aquaponics systems: 406.4 kg vs. 188 kg. The total income from snakehead and water spinach in aquaponics was 4 times higher than in normal farming systems: 1219.42 $US and 307.04 $US. It was especially not using any chemical during cultivating period in aquaponics that produce the fresh and healthy food to consumers. Based on our present findings might have important implications towards to manage any further development of snakehead industry, as well as contribute to applied aquaponics systems to other high value local species. Besides, using cycled and reusable and utilizing local materials will keep the aquaponics lasting and expanding to social life, especially in developing countries which are the main bow supplying food to feed the world. Moreover, under climate changing, applied aquaponics is meaningful in draught prone, flood prone and coastal saline affected soil region to produce fish and vegetable round the year.
Table 4 The production of water spinach in applied aquaponics system (SAQ) and normal planting systems – control experiment (VC). Number of harvests
1 2 3 4 5 6 7 8 Total Average STDVE
Average production (kg) /m2
Average production (kg)/bed (24 m2)
SAQ
VC
SAQ
VC
1.6 1.8 1.9 2.2 2.2 2.3 2.5 2.4 16.9 2.1 0.29
1.3 0.6 1.0 0.8 1.0 0.9 1.3 0.9 7.8 1.0 0.23
39.2 44 45.6 52 53.6 56 59.2 56.8 406.4 50.8 7.08
31.2 15.2 24.8 19.2 23.2 21.6 31.2 21.6 188 23.5 5.54
was 633.86 $US vs (−16.46) $US (Fig. 9b). The percentage of net profit in applied aquaponics was 108.24% highly potential attracting farmers investment while the initial net profit in normal farming systems was (−5.09%) (Fig. 9c). The fish in aquaponics used feed more efficiency with FCR: 1.25 vs. 2.25 and higher in survival rate that were increasing net profit. Therefore, it is necessary applying aquaponics to cultivate snakehead to increase the income and friendly to environment.
Declaration of Competing Interest The authors declare that there are no competing interests regarding the publication of this paper.
4. Conclusion Farming intensive fish requires a huge amount of good freshwater quality and discharges the wastewater back to outside environment. This study shows that it is more advantage to utilize available local materials and local species in aquaponics: using locally available coconut peat as a base soil to reduce the soil-less culture in the heavily salted soil cultivation area; plastic floating pond saving more money for
Acknowledgements The present study was supported by Saphenix Co., Ltd., Tra Vinh province, Vietnam; Tra Vinh University, Vietnam and Da–Yeh University, Taiwan.
Table 5 Income from snakehead and water spinach in two systems ($US). Products
Snakehead Water spinach Sum Initial investment cost (Instruction, electrical cost) Net profit
Applied aquaponics
Normal farming systems
Amount (kg)
Price ($US/kg)
Total ($US)
Amount (kg)
Price ($US/kg)
Total ($US)
366 406.4
2.61 0.65
955.26 264.16 1219.42 585.56 633.86
130 188
1.74 0.43
226.20 80.84 307.04 323.50 −16.46
The price of the products was the current price of the market in Vietnam for safe products. This was the real price that the farm was selling to the market. 7
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Fig. 9. (a) The income in (SAQ) and normal farming systems - control experiment (SC + VC). (b) The ratio between initial investment cost and net profit (c) Net profit in applied aquaponics and normal farming system.
Appendix A. Supplementary data
FAO (Food and Agriculture Organization of the United Nations), 2019. Fisheries and Aquaculture Department. Species Fact sheet. Channa striata (Bloch, 1973). http:// www.fao.org/fishery/species/3062/en. Farhana, T., Hasan, M.E., Mamun, A.A., Islam, M.S., 2016. Commercially culture potentiality of striped snakehead fish Channa striatus (Bloch, 1793) in earthen ponds of Bangladesh. Int. J. Pure Appl. Zool. 4 (2), 168–173. Available online: http://www. alliedacademies.org/articles/commercially-culture-potentiality-of-stripedsnakehead-fish-channa-striatus-bloch-1793-in-earthen-ponds-of-bangladesh.pdf. Hasan, N.B.A., 2014. Aquaponics System for Treat a Catfish Wastewater. Available online:. Thesis graduated from University – Faculty of Civil Engineering and Earth Resources – University Malaysia Pahang. http://umpir.ump.edu.my/id/eprint/ 9306/1/NURAIN%20BINTI%20ABU%20HASAN.PDF. Lan, L.M., Nguyen, T.H., Duong, N.L., 2011. Nuôi cá lóc (Channa sp.) trong bể lót bạt tại tỉnh Hậu Giang. In: Proceedings of the 4th Conference on Fisheries Science. Can Tho University. pp. 395–404. (In Vietnamese). Available online: http://www.vietlinh.vn/ nuoi-trong-thuy-san/ca-loc-lot-bat.pdf. Lennard, W.A., Leonard, B.V., 2005. A comparison of reciprocating flow versus constant flow in an integrated, gravel bed, aquaponic test system. Aquac. Int. 12 (6), 539–553. https://doi.org/10.1007/s10499-005-8528-x. Long, D.N., 2010. Textbook of Freshwater Aquaculture Technique: Bookcase of Can Tho University. Can Tho University (In Vietnamese). Mamat, N.Z., Shaari, M.I., Wahab, N.A.A.A., 2016. The production of catfish and vegetables in an aquaponic system. Fish. Aquacult. J. 7 (4), 1–3. https://doi.org/10.4172/ 2150-3508.1000181. Muthmainnah, D., 2013. Grow out of striped snakehead (Channa striata) in swamp water system using fences and cages. In: 4th International Conference on Biology, Environment and Chemistry IPCBEE. IACSIT Press, Singapore 58. pp. 52–55. Available online: https://pdfs.semanticscholar.org/a341/ e40a8a5b37dcbda0e1b15aead7400c83bf80.pdf. Nguyen, V.H., Tuyet-Hanh, T.T., Unger, F., Dang-Xuan, S., Grace, D., 2017. Food safety in Vietnam: where we are at and what we can learn from international experiences. Infect. Dis. Poverty 6 (1), 39. https://doi.org/10.1186/s40249-017-0249-7. Nha, N.V., 2012. Thực nghiệm nuôi cá lóc (Channa sp.) trong bể lót bạt ở xã Ninh Quới, huyện Hồng Dân, tỉnh Bạc Liêu. Thesis graduated from University – Department of Fisheries – Can Tho University (In Vietnamese). Petrea, S.M., Cristea, V., Dediu, L., Contoman, M., Lupoae, P., Mocanu, M., Coada, M.T., 2013. Vegetable production in an integrated aquaponic system with rainbow trout and spinach. Bull. UASVM Anim. Sci. Biotechnol. 70 (1), 45–54. https://doi.org/10. 15835/buasvmcn-asb:70:1:9485. Pham, V.H., Arthur, P.J., Oosterveer, M.P., van den Brink, P.L., Pham, T.M.H., 2016. Pesticide use in Vietnamese vegetable production: a 10-year study. Int. J. Agric. Sustainability 14 (3), 325–338. https://doi.org/10.1080/14735903.2015.1134395. Phong, N.B., 2012. Thực nghiệm nuôi cá lóc đen (Channa striata) trong bể bạt tại tỉnh Bạc Liêu. Thesis graduated from University – Department of Fisheries – Can Tho University (In Vietnamese). Rakocy, J., Masser, M., Losordo, T., 2006. Recirculating Aquaculture Tank Production Systems: Aquaponics – Integrating Fish and Plant Culture. SRAC Publication No.
Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.aquaeng.2020. 102057. References Adler, P.R., Harper, J.K., Wade, E.W., Takeda, F., Summerfelt, S.T., 2000a. Economic 307 analysis of an aquaponic system for the integrated production of rainbow trout and 308 plants. Int. J. Recirc. Aquacult. 1 (1), 15–34. https://doi.org/10.21061/ijra.v1i1. 1359. Adler, P.R., Harper, J.K., Takeda, F., Wade, E.M., Summerfelt, S.T., 2000b. Economic evaluation of hydroponics and other treatment options for phosphorus removal in aquaculture effluent. Hort Sci. 35 (6), 993–999. https://doi.org/10.21273/HORTSCI. 35.6.993. Amin, S.M.N., Muntaziana, M.P.A., Kamarudin, M.S., Rahim, A.A., Rahman, M.A., 2015. Effect of different stocking densities on growth and production performances of chevron snakehead Channa striata in fiberglass tanks. North Am. J. Aquacult. 77, 289–294. https://doi.org/10.1080/15222055.2015.1024361. Boyd, C.E., 1990a. Water Quality in Ponds for Aquaculture. Alabama Agricultural Experiment Station, Auburn University, Auburn, Alabama p. 482. Boyd, C.E., 1990b. Water Quality Management for Pond Fish Culture. Department of Fisheries and Allied Aquaculture. Agricultural Experiment Station, Auburn, Alabama, Birmingham Publishing Company, New York. Chung, D.M., Sinh, L.X., 2011. An analysis of snakehead value chain (Channa striata.) cultured in the Mekong Delta. In: The National Conference Proceedings on Aquaculture and Fisheries. Can Tho University 4. pp. 512–523. Da Rocha, A.F., Filho, M.L.B., Stech, M.R., da Silva, R.P., 2017. Lettuce production in aquaponic and bio floc systems with silver catfish Rhamdia quelen. Bol. Inst. Pesca. 44, 64–73. https://doi.org/10.20950/1678-2305.2017.64.73. De Koning, J.I.J.C., Crul, M.R.M., Wever, R., Brezet, J.C., 2015. Sustainable consumption in Vietnam: an explorative study among the urban middle class. Int. J. Consum. Stud. 39, 608–618. https://doi.org/10.1111/ijcs.12235. De Stefani, G., Tocchetto, D., Salvato, M., Borin, M., 2011. Performance of a floating treatment wetland for in-stream water amelioration in NE Italy. Hydrobiologia 674 (1), 157–167. https://doi.org/10.1007/s10750-011-0730-4. Endut, A., Jusoh, A., Ali, N., 2014. Nitrogen budget and effluent nitrogen components in aquaponics recirculation system. Desalin. Water Treat. 52 (4–6), 744–752. https:// doi.org/10.1080/19443994.2013.826336. Endut, A., Lananan, F., Abdul Hamid, S.H., Jusoh, A., Wan Nik, W.N., 2016. Balancing of nutrient uptake by water spinach (Ipomoea aquatica) and mustard green (Brassica juncea) with nutrient production by African catfish (Clarias gariepinus) in scaling aquaponic recirculation system. Desalin. Water Treat. 57 (60), 29531–29540. https://doi.org/10.1080/19443994.2016.1184593.
8
Aquacultural Engineering 89 (2020) 102057
T.T.N. Bich, et al.
Truong, T.T., Yap, M.H.T., Ineson, E.M., 2012. Potential Vietnamese consumers’ perceptions of organic foods. Br. Food J. Hyg. Rev. 114 (4), 529–543. https://doi.org/ 10.1108/00070701211219540. Van, P.T.T., Thich, C.V., 2014. Ảnh hưởng số lần cho ăn lên tốc độ tăng trưởng của cá lóc (Channa striata) nuôi trong hệ thống tuần hoàn. AGU J. Sc. 4, 79–84. Available online: http://www.agu.edu.vn:8080/bitstream/AGU_Library/2618/1/Bai%2014-phan %20Thi%20Thanh%20Van%20va%20Cao%20Van%20Thich.pdf. (In Vietnamese). Vietnam Ministry of Health, 2016. Joint Annual Health Review 2015 Strengthening Primary Health Care at the Grassroots Towards Universal Health Coverage. Available online:. Medical Publishing House. http://jahr.org.vn/downloads/ JAHR2015/JAHR2015_full_EN.pdf. Wahab, S.Z.A., Kadir, A.A., Hussain, N.H.N., Omar, J., Yunus, R., Baie, S., 2015. The effect of Channa striatus (Haruan) extract on pain and wound healing of post-lower segment caesarean section women. Evid. Based Complement. Altern. Med. 6. https:// doi.org/10.1155/2015/849647. Walter, R., Courtenay Jr., , Williams, J.D., 2004. Snakeheads (Pisces, Channidae) – A Biological Synopsis and Risk Assessment. U.S. Geological Survey Circular 1251. Available online:. https://nas.er.usgs.gov/taxgroup/fish/docs/ SnakeheadRiskAssessment.pdf.
454. Available online:. Southern Regional Aquaculture Center. http://www. gemstone.umd.edu/team-sites/classof2014/mega/documents/Rakocy_RAS.PDF. Sahid, N.A., Hayati, F., Rao, C.V., Ramely, R., Sani, I., Dzulkarnaen, A., Zakaria, Z., Hassan, S., Zahari, A., Ali, A.A., 2018. Snakehead consumption enhances wound healing? From tradition to modern clinical practice: a prospective randomized controlled trial. Evid. Complement. Alternat. Med. 9. https://doi.org/10.1155/2018/ 3032790. Sauthier, N., Grasmick, A., Blancheton, J.P., 1998. Biological denitrification applied to a marine closed aquaculture system. Water Res. 32 (6), 1932–1938. https://doi.org/ 10.1016/S0043-1354(97)00406-5. Simmons, L., Scott, S., 2007. Health concerns drive safe vegetable production in Vietnam. Leisa Mag. 23 (3), 22–23. Available online: http://lib.icimod.org/record/12722/ files/3548.pdf. Sinh, L.X., Navy, H., Pomeroy, R., 2014. Value chain analysis of snakehead fish in the lower Mekong Basin of Cambodia and Vietnam. Aquacult. Econ. Manage. 18 (1), 76–96. https://doi.org/10.1080/13657305.2014.855956. Tra Vinh Department of Natural Resource and Environment, 2018. Annual Report. Tra Vinh GSO (General Statistics Office), 2019. Available online: http:// thongketravinh.vn/.
9