Evaluation of single and multiple-ingredient Feeds for 7-d Posthatch Osteobrama belangeri larvae in clearwater system

Feeding trial was conducted to evaluate the growth performance and survival of 7-d post-hatch (dph) Osteobrama belangeri larvae on four different allochthonous feeds namely; a simple mixture of mustard oil cake and rice bran (1:1; D1), a multiple ingredient-based compound feed (D2) of rice bran, mustard oil cake, soybean meal, fishmeal and, vitamins and minerals (3.5:2:2:2:0.5, D2); crushed fresh Wolffia globosa (D3) and dry meal of W. globosa (D4). The trial was conducted for 21 days in clearwater system inside a wet laboratory. The 7-d old O. belangeri larvae (mean weight 2.0±0.04 mg; mean length 5.50±0.50 mm) were stocked @120 numbers in glass aquariums (60 cm×30 cm×30 cm) filled with 40 L conditioned groundwater and provided with continuous aeration. Larvae were fed three times a day (8.00 AM, 12.00 PM and 4.00 PM) at combined feeding rate @100%-200% of their biomass (dry matter basis) by offering 1/3 of daily ration on each occasion. The final mean weight, final mean length and specific growth rate of O. belangeri were significantly highest (p<0.001) for D2 (73.70±1.53 mg and 12.83±0.44 mm) followed by those of D1 (53.37±3.07 mg and 11.67±0.17 mm), D4 (46.03±2.11 mg and 10.17±0.33 mm) and D3 (27.87±0.58 mg and 9.83±0.44 mm), in order. Survival of O. belangeri varied between 30-62% but no significant differences (P>0.05) were established between treatments. The results of the present study indicated that 7-dph O. belangeri larvae could utilise dry meal of Wolffia as a single-ingredient feed in clearwater system.