Effect of water depth on growth and survival of the stinging catfish Heteropneustes fossilis (Bloch, 1794) in pond rearing system of a humid subtropical agroclimatic region

The growth, survival and proximate composition of Heteropneustes fossilis (Bloch, 1794) were studied under different water depths (30, 60, 90 and 120 cm) for a period of 10 months, with a temperature range of 31.5 to 7.8°C [(May-June; 26.5-31.5°C; Stage 1); (July-September; 28.8-32.6°C; Stage 2); (October-November; 15.5-28.4°C; Stage 3); (December-February; 7.8-15.7°C; Stage 4)] under earthen pond conditions in the humid subtropical climate of Tripura State, India. All the ponds were of equal size (168 m2; 14 m x 12 m) but with different water depths. The fishes were fed with a mixture of rice bran and mustard oil cake (1:1) @ 0.5-3% of their biomass. The growth, survival and proximate composition of fish were recorded in each stage. The average daily weight gain, feed conversion ratio, survival and proximate composition were found to be better in water depths of 60 cm and 90 cm during May to September when water temperature was ≥26.5°C. However, when water temperature was ≤21.4°C (October-February), growth and other attributes significantly reduced. Two-way ANOVA revealed that water depth and temperature, individually and interactively, affected the growth of H. fossilis. From this trial, it can be concluded that H. fossilis performs better when water depth is 60-90 cm and the ideal water temperature for the culture is 28.3-30.4°C. The study confirms the depth preference of H. fossilis under the humid subtropical condition and the information generatedwill help in the sustainable farming of this species. Keywords:Asian stingingcatfish, Water depth,Temperature, Growth, Survival, Proximate composition