In total, 240 fish (mean weight + SD, 15.8 + 0.3 g) were randomly
assigned to 12, 120 l outdoor circular tanks. Tanks were individually
aerated and supplied with water from a header tank at a rate
of 5 l h1. The tanks were shaded and the water remained clear
throughout the feeding trials. Mean ambient water temperature
during the feeding experiments was 27 ± 2.2 C. Fish were fed to
apparent satiation twice a day, at 0700 and 1800, by slowly introducing
feed until the feeding response ceased. Each of the four
diets was fed to three replicate groups, each of 20 fish, and records
of feed consumption were kept for each treatment group. Weight
gain, specific growth rate (SGR), and food conversion ratio (FCR),
were calculated as parameters of growth and feed utilisation
(Table 3).