Optimization of stocking density and feeding ration for rearing of stunted Labeo rohita fingerlings in cages

Abstract

Aim: To rear stunted Labeo rohita fingerlings in cages and determine the optimum stocking density and feeding ration for better growth performance of fishes. Methodology: Eight-month-old stunted fingerlings of Labeo rohita (14.65cm/38.23g) were stocked in floating net square cages at different stocking densities (10, 15, 20 and 25 fishm-2) and fed with different feeding ration (3%, 4%, 5% and 6% of body weight), further reared for 330 days and fed twice a day with commercial floating pellets with 25% crude protein. The study followed 4*4 factorial design and were triplicated for each treatment and level. Results: The study found a decrease in the final body weight, average body weight gain, and specific growth rate with increasing stocking density. The highest final body weight (732.64 g), body weight gain (694.30 g) and specific growth rate (0.89 % day-1) were recorded in 10/m2 stocking density with feed ration of 6% body weight. In contrast to this, fish reared in higher stocking density (25/m2) exhibited poor feed conversion ratio. Fish reared in lower stocking density (10/m2) and fed with 6% feeding ration displayed an enhanced feed conversion ratio, feed efficiency ratio and protein efficiency ratio which indicated that rearing of stunted rohu in intensive cage culture at lower stocking density (10/m2) with higher feeding ration (6%) increase their feed utilization capacity. Interpretation: Rearing of stunted rohu in intensive cage culture is possible, however, the stocking density and feeding ration should be 10/m2 and 6%, respectively, compared to traditional cage practices, in order to reduce stress and to get optimum production. Key words: Cage culture, Feeding ration, Fingerling, Labeo rohita, Stocking density