Potential of earthworm (Eisenia foetida) as dietary protein source for rohu (Labeo rohita) advanced fry

Earthworm, a non-conventional protein source with 520–530 g protein kg−1 on dry matter basis was used in three forms viz. (i) whole earthworm (ii) earthworm custard, and (iii) pelleted earthworm diet to prepare three iso-nitrogenous (500 g protein kg−1 diet) and iso-caloric (17.0 MJ kg−1 diet) experimental diets. The formulated diets were fed ad libitum twice daily to Labeo rohita advanced fry (0.71 ± 0.04 g) in triplicates for a period of 35 days. In each replicate, 10 fish were stocked. The 300 L fiberglass-reinforced plastic tanks containing 100 L of water with the provision of continuous aeration were used for rearing the fish. At the end of experiment, the weight gain (g), food conversion ratio, specific growth rate, protein efficiency ratio, protein retention efficiency (%), and energy retention efficiency (%) of fish fed pelleted earthworm diet (2.19, 1.58, 4.21, 1.26, 23.0, and 18.6, respectively) was significantly better (p < 0.05) than the corresponding values of whole earthworm (1.53, 2.30, 3.38, 0.84, 14.34, and 11.93, respectively) and earthworm custard (0.94, 3.18, 2.42, 0.62, 10.50, and 8.21, respectively) fed diets. The experiment results indicated that the pelleted earthworm diet could be used in rearing of rohu advanced fry.