Abstract

Mukti Pada Bag , Subhas Chandra Mahapatra , Pavuluri Srinivasa Rao and Debajyoti Chakrabarty

A comprehensive trial was undertaken to assess the effect of various types of low cost nonconventional fish feed on the biomass conversion rate as well as on gonad (ovarian) weight in Mozambique tilapia, Oreochromis mossambicus. Three groups of juvenile fish (5.0 ± 0.15 g; 4.5 ± 0.12 cm) were fed with three different types of feeds with earthworm meal (EWM), slaughter house offal meal (SOM) and hydrated poultry feather meal (PFM). These fish feeds were isonitrogenus (30 g 100 g–1 ) and isocaloric (4 Kcal g–1 ) in nature. The EWM made with dry earthworm dust, rice bran, mustard oil cake and eggshell powder proved to be the best and economical feed among the three feed tested. Significant difference (P<0.05) in body weight gain, protein efficiency ratio and gonadosomatic index were observed among fish fed the EWM, SOM and PFM diets. No significant differences (P<0.05) in feed conversion ratio, energy retention and hepatosomatic index were observed. Among the dietary treatment groups, significantly lower (P<0.05) moisture content of body and higher whole-body protein were also found in EWM diets. The earth-worm possibly contained better quality of protein which in turn influenced somatic as well as reproductive growth of those fish. The study suggests that the EWM diet, which led to be significantly higher (P<0.05) growth and nutrient utilization than the other two diets in tilapia, O. mossambicus, may be used for pond culture of this species.