Utilization of fish offal meal in the diet of Clarias gariepinus fingerlings

Abstract

A feeding trial was conducted to investigate effect of replacing fish meal (FM) at 0, 25, 50, 75 and 100% with fish offal meal (FOM) in the diets of Clarias gariepinus fingerlings. At the start of experiment, ten glass aquaria of size 70 cm x 45 cm x 40 cm/each, filled with well water up to 70 L of its volume were stocked with 100 fingerlings (mean weight, 1.33±0.04 g and mean length 2 cm each) at 20 fish per treatment, replicated twice in a complete randomized design. Five experimental diets (D₁-D₅) including the control were formulated to be isocaloric (11.11 kcal/kg) and isonitrogeneous (40% crude protein). The fingerlings were fed at 5% body weight with the test diets for 70 days. It was observed that fish fed D₃ (50% FOM) exhibited the best feed utilization in terms of final mean weight gain (22.98±0.01)g; specific growth rate (1.76±0.01) and feed conversion ratio (1.09±0.06). Net protein utilization was significantly (p˂0.05) highest in fish fed D₄ (19.77±0.06). Calcium (2.45%) and phosphorus levels (0.97%) were significantly (p ˂0.05) highest in fish fed D₅. It could be deduced from results that 50% replacement of fish meal with fish offal meal (guts, scales and fins) in diets of C. gariepinus fingerlings would give optimal feed utilization without compromising growth rate.

Keywords: Aquaculture, fish nutrition, feed utilization, minerals, Clarias gariepinus