Effect of organic and inorganic fertilizers on natural food composition and performance of African catfish (Clarias gariepinus) fry produced under artificial propagation

Demand for fish in both rural and urban areas is very high in Tanzania. In recent times, the African catfish, Clarias gariepinus, has gained popularity in the aquaculture sector of Tanzania. However, many aquaculture farmers face the challenge of unreliable supply of seed due to difficulties of reproducing in captivity and high larvae mortality. The study was conducted to determine the effect of organic and inorganic fertilizers on natural food composition and performance of African catfish (C. gariepinus) fry produced under artificial propagation. The results indicated that abundance of natural food (phytoplankton) were significantly higher (P<0.05) in di-ammonium phosphate (DAP) fertilizer applied tanks compared to other treatments. While zooplankton diversity were higher in chicken manure applied tanks compared to other treatments. Individual final mean weight, weight gain and specific growth rate were not significantly different (P>0.05) between DAP fertilizer and chicken manure treatments across stocking densities (5fry/m2 and 10fry/m2), but were significantly higher than the control. Survival rates were not significantly different (P>0.05) between chicken manure and DAP fertilized treatments across stocking densities but differed significantly (P<0.05) from the control. Water quality parameters were found to be within the optimum range for both experiments. In conclusion, the study indicated that higher phytoplankton abundance are attained with DAP fertilized tanks and zooplankton diversity were higher in chicken manure applied tanks. Fish growth performance was higher in chicken manure treatment at low stocking density (5fry/m2). Therefore, it is recommended that for better growth and survival in aquaculture practices, catfish fry should be raised in DAP or chicken manure fertilized tanks at low stocking density (5fry/m2).