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Growth of Tilapia aurea in ponds receiving poultry wastes
Aquaculture, 20 (1980) 117-121 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
GROWTH OF TILAPIA WASTES
A UREA
117
IN PONDS RECEIVING POULTRY
ROBERT P. BURNS and ROBERT R. STICKNEY Department of Wildlife and Fisheries Sciences, TX 77843 (U.S.A.) (Accepted
Texas A&M University,
College Station,
5 November 1979)
ABSTRACT Bums, R.P. and Stickney, R.R., 1980. Growth of Tilapia aurea in ponds receiving poultry wastes. Aquaculture, 20: 117-121. Tilapia aurea fry were stocked in five 0.05 ha ponds at 8000 fish/ha during June 1977. Four ponds received the wastes from 500, 1000, 2000 and 4000 laying hens/ha, respectively, while the fifth pond received no poultry wastes. After a 150-day growing period, final mean fish weights and average daily production paralleled the rates of organic fertilization. T. aurea averaged only 46 g in the pond which received no organic fertilization, but reached an average of 304 g in the pond fertilized by the wastes from 4000 hens/ha. Thus, T. aureh can be reared to market-size in Texas within a single growing season if sufficient levels of nutrient are available. Survival reached or exceeded 95% in all five ponds. Water quality remained within acceptable limits throughout the experiment, although the effects of organic fertilization on water quality were apparent. INTRODUCTION
In Asia, fish pond systems have traditionally been utilized as receptacles for terrestrial animal wastes (Bardach et al., 1972). More recently, studies on the utilization of organic fertilizers in aquaculture have been undertaken in several other parts of the world, including Israel (Schroeder, 1974, 1975a,b; Moav et al., 1977; Rappaport et al., 1977; Rappaport and Sarig, 1978) and the United States (Buck et al., 1978a,b; Maddox et al., 1978; Stickney and Hesby, 1978; Stickney et al., 1977, 1979). Before adequate models of culture systems receiving organic fertilizers can be developed it is necessary to obtain some indication as to the amounts of various types of organic wastes which can be safely added to culture ponds containing various species of organisms and reared in different climates. For Texas, information on the optimum swine manuring rate for ponds containing tilapia has been obtained (Stickney, et al., 1977, 1979; Stickney and Hesby, 1978). The present study examined the growth of Tilapia aurea in ponds receiving various levels of poultry waste. In addition to attempting to find the desired rate of poultry waste addition for optimum fish growth and produc-
118
tion, goals of this study included determining whether or not marketable T.
aurea could be produced in Texas within a growing season without supple-
mental feeding, and determining the effects of increasing levels of organic fertilization on water quality. MATERIALS
AND METHODS
The research was conducted during the summer and fall, 1977 in five 0.05 ha earthen ponds with maximum depth of 2 m at the Aquaculture Research Center of the Texas Agricultural Experiment Station. Ponds were stocked on 1 June with 400 T. aurea (8000 fish/ha) approximately 4 weeks of age and averaging 0.15-0.20 g. The fish were fed a commercial diet treated with 17 or-ethynyltestosterone for 3 weeks in the laboratory prior to stocking utilizing the technique developed by Guerrero (1975). This was done in an attempt to produce all-male populations. Prior to filling in early May, laying hen houses were constructed over four of the ponds. The houses were open-walled, metal-roofed structures which supported one or two rows of cages and provided the birds with protection from direct sunlight and rain. Eggs were collected and the hens fed to excess daily. One pond received no poultry wastes; others received the wastes from 25, 50,100 or 200 laying hens (500, 1000,200O and 4000 hens/ha, respectively). The fish were harvested at the time of pond draining 150 days after initial stocking. All T. aurea were individually weighed to the nearest gram. Average final weights, daily production and survival percentages were calculated. One hundred fish from each pond were sexed by gonadal examination to determine the effectiveness of the hormone treatment. Three fish from each pond were examined for Salmonella bacteria. Daily measurements of temperature and ammonia (APHA, 1975) were obtained at about 11.00 h. Orthophosphates, nitrates, nitrites and pH were determined weekly; and total alkalinity and hardness were measured monthly (APHA, 197 5). Water samples from each pond collected on 7 July and 28 September were characterized microscopically for dominant phytoplankton species. RESULTS
AND DISCUSSION
Table I presents the final mean weights, average daily production, percentages males recovered and percentage survival of T. aurea in each pond upon termination of the 150-day study. Final mean weights and average daily production both increased in direct proportion to the addition of poultry waste. At the highest fertilization rate, fish averaging over 300 g were obtained by the end of the study; those fish were well within the acceptable size range for the United States market.
119
TABLE I Summary of Tilapia aurea growth, production, receiving poultry wastes Measurement
Hens/pond 0
Final mean weight (g) Average production (kg ha-’ day-’ ) Calculated manuring rate (kg ha-’ day-’ dry matter) Ratio of manure added to fish produced Percentage males Percentage survival
percentage males and survival in ponds
46 2.4
25
50
100
200
108
193
238
304
5.5
10.7
12.0 50
0
12.5
25
100 100
2.3 96 96
2.3 96 98
4.2 100 100
16.2 100 6.2 98 95
Production values ranged widely among the five ponds, with the highest being 16.2 kg ha-’ day-’ in the pond receiving the highest rate of poultry wastes (Table I). Somewhat higher production rates have been achieved by employing liquified cow manure as organic fertilizer (Moav et al., 1977). Calculated manuring rates (kg ha-’ day-’ of dry matter entering each pond) are presented in Table I. The calculations are based upon the assumption that an average 1600 g laying hen produces dry weight manure at the rate of 0. 025 kg/day. The ratios of dry weight manure added daily to average daily fish production figures are also presented in Table I. These values indicate that the manure is more efficiently utilized at the lower rates of addition and that nutrients are apparently present in excess at the highest rates, even though fish growth continued to improve as manuring rate increased. The feeding of androgens prior to fish stocking was effective in producing a preponderance of males in each of the five experimental ponds (Table I). Limited reproduction occurred by mid-September in ponds having less than 100% males, but juveniles did not represent sufficient numbers or size to be competitive with fish from the initial stocking. Survival was excellent in all of the experimental ponds (Table I). The three fish collected from each pond and subjected to microbiological examination were all found to be free of Salmonetla. Water temperature was consistent among the five ponds, remaining at or above 28°C from the initiation of the study until late September, after which a steady decline occurred. Termination of the study at the end of October coincided with water temperatures of 2O”C, which was considered to be within the range where tilapia growth is curtailed. The maximum total ammonia level recorded (2.4 mg/l) was associated with the pond which received the highest level of poultry waste. Other experiments with T. aurea have demonstrated that the species can tolerate total
120
ammonia levels in excess of 20 mg/l under conditions similar to those which prevailed during the present study (Stickney et al., 1977; Redner and Stickney, 1979). Pond pH ranged from 7.2 to 9.3, with largest differences with time occurring in ponds which received the highest levels of fertilization. Ammonia toxicity is dependent to a large extent on pH (Goldstein and Forster, 1970) and increases with increasing pH. Highest ammonia levels (2.4 mg/l) corresponded with pH values of only 8.0, which was sufficiently low to ensure that most of the ammonia was in the ionized, non-toxic form. Nitrite was consistently below 0.1 mg/l in all ponds throughout the study. Nitrate averaged 2.9 mg/l in the pond receiving no poultry wastes and gradually increased as the number of laying hens over the ponds decreased. The nitrate level in the pond over which 200 hens were placed averaged only 1.4 mg/ 1. The observed phenomenon may have been related to relative rates of photosynthesis among the five ponds. As manuring rate increased, photosynthetic organisms may have been more efficient at removing nitrate because of competition and a higher rate or productivity. Alternatively, higher productivity among invertebrates in ponds receiving high levels of organic fertilization may have been responsible for the high rate of nitrate removal which apprently occurred. Orthophosphate levels increased in direct proportion with manuring rates. The levels of orthophosphate in the ponds receiving no poultry wastes and the pond receiving the wastes from 25 birds were consistently below 0.5 mg/l throughout the study. The maximum level observed (>5.0 mg/l) occurred in the pond receiving the wastes from 200 hens. Some oscillations in orthophosphate occurred, with a general decline becoming apparent as water temperature began to cool. All ponds were similar with respect to total alkalinity and hardness. Alkalinity ranged from 80 to 140 mg/l (as CaCO,), with an average of 105 mg/l. Hardness ranged from 125 to 265 mg/l (as CaCO,), with an average of 178 mg/l. An indication of photosynthetic activity was obtained by bi-weekly Secchi disc measurements. Disappearance of the Secchi disc in the four ponds receiving the lowest rates of organic material ranged from about 50 to 75 cm throughout the study period. The pond receiving the waste from 200 laying hens showed a pattern of disappearance consistantly between 30 and 40 cm. The dominant alga in the four ponds which received poultry wastes was a colonial species of Anabaena. Had the phytoplankton bloom been characterized by smaller colonies or a single-celled species, significantly reduced water clarity might have occurred. Turbidity associated with the pond which received no poultry waste appeared to be due primarily to suspended sediment particles. ACKNOWLEDGEMENTS
This study was supported, in part, by the Texas Agricultural Experiment
121
Station under project H-2831. The authors wish to thank Ranzell Nickelson for bacteriological analyses and Lenton Rowland for providing the hens and feed. In addition, W.A. Isbell provided valuable assistance in the construction and maintenance of the hen housing facility.
REFERENCES American Public Health Association, 1975. Standard Methods for the Treatment of Water and Wastewater. American Public Health Association, Washington, D.C., 14th edn., 1193 pp. Bardach, J.E., Ryther, J.H. and McLamey, W.O., 1972. Aquaculture. Wiley-Interscience, New York, N.Y., 868 pp. Buck, H., Baur, R.J. and Rose, CR., 1978a. Polyculture of Chinese carps in ponds with swine wastes. In: R-0. Smitherman, W.L. Shelton and J.H. Grover (Editors), Culture of Exotic Fishes Symposium Proceedings. Fish Culture Section, Am. Fish. Sot., Auburn, AL, pp. 144-155. Buck, D.H., Baur, R.J. and Rose, C.R., 1978b. Utilization of swine manure in a polyculture of Asian and North American fishes. Trans. Am. Fish. Sot., 107: 216-222. Goldstein, L. and Forster, R.P., 1970. Nitrogen metabolism in fishes. In: J.W. Campbell (Editor), Comparative Biochemistry of Nitrogen Metabolism. Academic Press, New York, N.Y., pp_ 495-518. Guerrero, R.D., 1975. Use of androgens for the production of all-male TiEapiaaurea (Steindachner). Trans. Am. Fish. Sot., 104: 342-348. Maddox, J.J., Behrends, L.L., Madewell, C.E. and Pile, R.S., 1978. Algae-wine manure system for production of silver carp, bighead carp and tilapia. In: R-0. Smitherman, W..L. Shelton and J.H. Grover (Editors), Culture of Exotic Fishes Symposium Proceedings. Fish Culture Section, Am. Fish. Sot., Auburn, AL, pp. 109-120. Moav, R., Wohlforth, G., Schroeder, G.L., Hulata, G. and Barash, H., 1977. Intensive polyculture of fish in freshwater ponds. I. Substitution of expensive feeds by liquid cow manure. Aquaculture, 10: 25-43. Rappaport, U. and Sarig, S., 1978. The results of manuring on intensive growth fish farming at the Ginosar Station ponds in 1977. Bamidgeh, 30: 27-36. Rappaport, U., Sarig, S. and Berjerano, Y., 1977. Observations on the use of organic fertilizers in intensive fish farming at the Ginosar Station in 1976. Bamidgeh, 29: 57-70. Redner, B.D. and Stickney, R.R., 1979. Acclimation to ammonia by Tilapiu aurea. Trans. Am. Fish. Sot., 1.08: 383-388. Schroeder, G., 1974. Use of fluid cowshed manure in fish ponds. Bamidgeh, 26( 3): 84-96. Schroeder, G., 1975a. Nighttime material balance for oxygen in fish ponds receiving organic wastes. Bamidgeh, 27: 65-74. Schroeder, G., 197513. Some effects of stocking fish in waste treatment ponds. Water Res., 9: 591-593. Stickney, R.R. and Hesby, J.H., 1978, Tilapia production in ponds receiving swine wastes. In: R-0. Smitherman, W.L. Shelton and J.H. Grover (Editors), Culture of Exotic Fishes Symposium Proceedings. Fish Culture Section, Am. Fish. Sot., Auburn, AL, pp. 90101. Stickney, R.R., Rowland, L.O. and Hesby, J.H., 1977. Water quality-TiZupiu aurea interactions in ponds receiving swine and poultry wastes. Proc. World Maricult. Sot., 8: 55-71. Stickney, R.R., Hesby, J.H., McGeachin, R.B. and Isbell, W.A., 1979. Growth of Tilapia nilofica in ponds with differing histories of organic fertilization. Aquaculture, 17: 189194.
GROWTH OF TILAPIA WASTES
A UREA
117
IN PONDS RECEIVING POULTRY
ROBERT P. BURNS and ROBERT R. STICKNEY Department of Wildlife and Fisheries Sciences, TX 77843 (U.S.A.) (Accepted
Texas A&M University,
College Station,
5 November 1979)
ABSTRACT Bums, R.P. and Stickney, R.R., 1980. Growth of Tilapia aurea in ponds receiving poultry wastes. Aquaculture, 20: 117-121. Tilapia aurea fry were stocked in five 0.05 ha ponds at 8000 fish/ha during June 1977. Four ponds received the wastes from 500, 1000, 2000 and 4000 laying hens/ha, respectively, while the fifth pond received no poultry wastes. After a 150-day growing period, final mean fish weights and average daily production paralleled the rates of organic fertilization. T. aurea averaged only 46 g in the pond which received no organic fertilization, but reached an average of 304 g in the pond fertilized by the wastes from 4000 hens/ha. Thus, T. aureh can be reared to market-size in Texas within a single growing season if sufficient levels of nutrient are available. Survival reached or exceeded 95% in all five ponds. Water quality remained within acceptable limits throughout the experiment, although the effects of organic fertilization on water quality were apparent. INTRODUCTION
In Asia, fish pond systems have traditionally been utilized as receptacles for terrestrial animal wastes (Bardach et al., 1972). More recently, studies on the utilization of organic fertilizers in aquaculture have been undertaken in several other parts of the world, including Israel (Schroeder, 1974, 1975a,b; Moav et al., 1977; Rappaport et al., 1977; Rappaport and Sarig, 1978) and the United States (Buck et al., 1978a,b; Maddox et al., 1978; Stickney and Hesby, 1978; Stickney et al., 1977, 1979). Before adequate models of culture systems receiving organic fertilizers can be developed it is necessary to obtain some indication as to the amounts of various types of organic wastes which can be safely added to culture ponds containing various species of organisms and reared in different climates. For Texas, information on the optimum swine manuring rate for ponds containing tilapia has been obtained (Stickney, et al., 1977, 1979; Stickney and Hesby, 1978). The present study examined the growth of Tilapia aurea in ponds receiving various levels of poultry waste. In addition to attempting to find the desired rate of poultry waste addition for optimum fish growth and produc-
118
tion, goals of this study included determining whether or not marketable T.
aurea could be produced in Texas within a growing season without supple-
mental feeding, and determining the effects of increasing levels of organic fertilization on water quality. MATERIALS
AND METHODS
The research was conducted during the summer and fall, 1977 in five 0.05 ha earthen ponds with maximum depth of 2 m at the Aquaculture Research Center of the Texas Agricultural Experiment Station. Ponds were stocked on 1 June with 400 T. aurea (8000 fish/ha) approximately 4 weeks of age and averaging 0.15-0.20 g. The fish were fed a commercial diet treated with 17 or-ethynyltestosterone for 3 weeks in the laboratory prior to stocking utilizing the technique developed by Guerrero (1975). This was done in an attempt to produce all-male populations. Prior to filling in early May, laying hen houses were constructed over four of the ponds. The houses were open-walled, metal-roofed structures which supported one or two rows of cages and provided the birds with protection from direct sunlight and rain. Eggs were collected and the hens fed to excess daily. One pond received no poultry wastes; others received the wastes from 25, 50,100 or 200 laying hens (500, 1000,200O and 4000 hens/ha, respectively). The fish were harvested at the time of pond draining 150 days after initial stocking. All T. aurea were individually weighed to the nearest gram. Average final weights, daily production and survival percentages were calculated. One hundred fish from each pond were sexed by gonadal examination to determine the effectiveness of the hormone treatment. Three fish from each pond were examined for Salmonella bacteria. Daily measurements of temperature and ammonia (APHA, 1975) were obtained at about 11.00 h. Orthophosphates, nitrates, nitrites and pH were determined weekly; and total alkalinity and hardness were measured monthly (APHA, 197 5). Water samples from each pond collected on 7 July and 28 September were characterized microscopically for dominant phytoplankton species. RESULTS
AND DISCUSSION
Table I presents the final mean weights, average daily production, percentages males recovered and percentage survival of T. aurea in each pond upon termination of the 150-day study. Final mean weights and average daily production both increased in direct proportion to the addition of poultry waste. At the highest fertilization rate, fish averaging over 300 g were obtained by the end of the study; those fish were well within the acceptable size range for the United States market.
119
TABLE I Summary of Tilapia aurea growth, production, receiving poultry wastes Measurement
Hens/pond 0
Final mean weight (g) Average production (kg ha-’ day-’ ) Calculated manuring rate (kg ha-’ day-’ dry matter) Ratio of manure added to fish produced Percentage males Percentage survival
percentage males and survival in ponds
46 2.4
25
50
100
200
108
193
238
304
5.5
10.7
12.0 50
0
12.5
25
100 100
2.3 96 96
2.3 96 98
4.2 100 100
16.2 100 6.2 98 95
Production values ranged widely among the five ponds, with the highest being 16.2 kg ha-’ day-’ in the pond receiving the highest rate of poultry wastes (Table I). Somewhat higher production rates have been achieved by employing liquified cow manure as organic fertilizer (Moav et al., 1977). Calculated manuring rates (kg ha-’ day-’ of dry matter entering each pond) are presented in Table I. The calculations are based upon the assumption that an average 1600 g laying hen produces dry weight manure at the rate of 0. 025 kg/day. The ratios of dry weight manure added daily to average daily fish production figures are also presented in Table I. These values indicate that the manure is more efficiently utilized at the lower rates of addition and that nutrients are apparently present in excess at the highest rates, even though fish growth continued to improve as manuring rate increased. The feeding of androgens prior to fish stocking was effective in producing a preponderance of males in each of the five experimental ponds (Table I). Limited reproduction occurred by mid-September in ponds having less than 100% males, but juveniles did not represent sufficient numbers or size to be competitive with fish from the initial stocking. Survival was excellent in all of the experimental ponds (Table I). The three fish collected from each pond and subjected to microbiological examination were all found to be free of Salmonetla. Water temperature was consistent among the five ponds, remaining at or above 28°C from the initiation of the study until late September, after which a steady decline occurred. Termination of the study at the end of October coincided with water temperatures of 2O”C, which was considered to be within the range where tilapia growth is curtailed. The maximum total ammonia level recorded (2.4 mg/l) was associated with the pond which received the highest level of poultry waste. Other experiments with T. aurea have demonstrated that the species can tolerate total
120
ammonia levels in excess of 20 mg/l under conditions similar to those which prevailed during the present study (Stickney et al., 1977; Redner and Stickney, 1979). Pond pH ranged from 7.2 to 9.3, with largest differences with time occurring in ponds which received the highest levels of fertilization. Ammonia toxicity is dependent to a large extent on pH (Goldstein and Forster, 1970) and increases with increasing pH. Highest ammonia levels (2.4 mg/l) corresponded with pH values of only 8.0, which was sufficiently low to ensure that most of the ammonia was in the ionized, non-toxic form. Nitrite was consistently below 0.1 mg/l in all ponds throughout the study. Nitrate averaged 2.9 mg/l in the pond receiving no poultry wastes and gradually increased as the number of laying hens over the ponds decreased. The nitrate level in the pond over which 200 hens were placed averaged only 1.4 mg/ 1. The observed phenomenon may have been related to relative rates of photosynthesis among the five ponds. As manuring rate increased, photosynthetic organisms may have been more efficient at removing nitrate because of competition and a higher rate or productivity. Alternatively, higher productivity among invertebrates in ponds receiving high levels of organic fertilization may have been responsible for the high rate of nitrate removal which apprently occurred. Orthophosphate levels increased in direct proportion with manuring rates. The levels of orthophosphate in the ponds receiving no poultry wastes and the pond receiving the wastes from 25 birds were consistently below 0.5 mg/l throughout the study. The maximum level observed (>5.0 mg/l) occurred in the pond receiving the wastes from 200 hens. Some oscillations in orthophosphate occurred, with a general decline becoming apparent as water temperature began to cool. All ponds were similar with respect to total alkalinity and hardness. Alkalinity ranged from 80 to 140 mg/l (as CaCO,), with an average of 105 mg/l. Hardness ranged from 125 to 265 mg/l (as CaCO,), with an average of 178 mg/l. An indication of photosynthetic activity was obtained by bi-weekly Secchi disc measurements. Disappearance of the Secchi disc in the four ponds receiving the lowest rates of organic material ranged from about 50 to 75 cm throughout the study period. The pond receiving the waste from 200 laying hens showed a pattern of disappearance consistantly between 30 and 40 cm. The dominant alga in the four ponds which received poultry wastes was a colonial species of Anabaena. Had the phytoplankton bloom been characterized by smaller colonies or a single-celled species, significantly reduced water clarity might have occurred. Turbidity associated with the pond which received no poultry waste appeared to be due primarily to suspended sediment particles. ACKNOWLEDGEMENTS
This study was supported, in part, by the Texas Agricultural Experiment
121
Station under project H-2831. The authors wish to thank Ranzell Nickelson for bacteriological analyses and Lenton Rowland for providing the hens and feed. In addition, W.A. Isbell provided valuable assistance in the construction and maintenance of the hen housing facility.
REFERENCES American Public Health Association, 1975. Standard Methods for the Treatment of Water and Wastewater. American Public Health Association, Washington, D.C., 14th edn., 1193 pp. Bardach, J.E., Ryther, J.H. and McLamey, W.O., 1972. Aquaculture. Wiley-Interscience, New York, N.Y., 868 pp. Buck, H., Baur, R.J. and Rose, CR., 1978a. Polyculture of Chinese carps in ponds with swine wastes. In: R-0. Smitherman, W.L. Shelton and J.H. Grover (Editors), Culture of Exotic Fishes Symposium Proceedings. Fish Culture Section, Am. Fish. Sot., Auburn, AL, pp. 144-155. Buck, D.H., Baur, R.J. and Rose, C.R., 1978b. Utilization of swine manure in a polyculture of Asian and North American fishes. Trans. Am. Fish. Sot., 107: 216-222. Goldstein, L. and Forster, R.P., 1970. Nitrogen metabolism in fishes. In: J.W. Campbell (Editor), Comparative Biochemistry of Nitrogen Metabolism. Academic Press, New York, N.Y., pp_ 495-518. Guerrero, R.D., 1975. Use of androgens for the production of all-male TiEapiaaurea (Steindachner). Trans. Am. Fish. Sot., 104: 342-348. Maddox, J.J., Behrends, L.L., Madewell, C.E. and Pile, R.S., 1978. Algae-wine manure system for production of silver carp, bighead carp and tilapia. In: R-0. Smitherman, W..L. Shelton and J.H. Grover (Editors), Culture of Exotic Fishes Symposium Proceedings. Fish Culture Section, Am. Fish. Sot., Auburn, AL, pp. 109-120. Moav, R., Wohlforth, G., Schroeder, G.L., Hulata, G. and Barash, H., 1977. Intensive polyculture of fish in freshwater ponds. I. Substitution of expensive feeds by liquid cow manure. Aquaculture, 10: 25-43. Rappaport, U. and Sarig, S., 1978. The results of manuring on intensive growth fish farming at the Ginosar Station ponds in 1977. Bamidgeh, 30: 27-36. Rappaport, U., Sarig, S. and Berjerano, Y., 1977. Observations on the use of organic fertilizers in intensive fish farming at the Ginosar Station in 1976. Bamidgeh, 29: 57-70. Redner, B.D. and Stickney, R.R., 1979. Acclimation to ammonia by Tilapiu aurea. Trans. Am. Fish. Sot., 1.08: 383-388. Schroeder, G., 1974. Use of fluid cowshed manure in fish ponds. Bamidgeh, 26( 3): 84-96. Schroeder, G., 1975a. Nighttime material balance for oxygen in fish ponds receiving organic wastes. Bamidgeh, 27: 65-74. Schroeder, G., 197513. Some effects of stocking fish in waste treatment ponds. Water Res., 9: 591-593. Stickney, R.R. and Hesby, J.H., 1978, Tilapia production in ponds receiving swine wastes. In: R-0. Smitherman, W.L. Shelton and J.H. Grover (Editors), Culture of Exotic Fishes Symposium Proceedings. Fish Culture Section, Am. Fish. Sot., Auburn, AL, pp. 90101. Stickney, R.R., Rowland, L.O. and Hesby, J.H., 1977. Water quality-TiZupiu aurea interactions in ponds receiving swine and poultry wastes. Proc. World Maricult. Sot., 8: 55-71. Stickney, R.R., Hesby, J.H., McGeachin, R.B. and Isbell, W.A., 1979. Growth of Tilapia nilofica in ponds with differing histories of organic fertilization. Aquaculture, 17: 189194.