After the fish started to eat the basal diet for 2 weeks, they were graded to a similar size (6.67 ± 0.03 g) and randomly stocked into 18 rectangular fiberglass tanks (300 L) at 30 fish per tank.
The experimental tanks were connected with a closed indoor recirculating system with continuous filtered freshwater and aeration to maintain the dissolved oxygen level above saturation.
For the next 8 weeks, fish in triplicate were fed their respective diets twice daily manually to visual satiation at 09:00 and 17:00, and feed consumption was recorded daily. Fish were weighed every 4 weeks, and mortality and deformity were checked daily.
Natural light–dark cycle was used in the whole experimental period.
The culture tanks were cleaned by siphoning off accumulated waste materials and water quality parameters were monitored twice weekly. Throughout the experimental period, water temperature, dissolved O2, pH and ammonia were maintained at about 27.5 ± 1.3 °C, 7.65 ± 0.14 mg/L, 7.85 ± 0.10 and 0.16 ± 0.02 mg/L, respectively.