Effect of dietary lipid sources on rabbitfish (Siganus rivulatus) performance and health status under biofloc system condition during the nursery phase

This study was conducted to estimate the negative effect of feeding a commercial diet containing vegetable oils on S. revulatuse performance during the nursery phase under biofloc system conditions. Three experimental diets were formulated; a control diet supplemented with 4% cod liver oil (CLO), a diet supplemented with 4% coconut oil (CO), and a diet supplemented with 4% sunflower oil (SO). Fry were randomly stocked into nine experimental tanks of 15 fry/tank with an initial weight of 0.76 ± 0.03g/fry. The experiment was extended for 60 days. The fish fed on the CLO diet recorded the highest significant growth performance parameters, while no significant difference was recorded between SO diet and the CO diet. The survival rate showed no significant difference among the three treatments. Gill sections of S. rivulatus fed CLO and CO diets showed mild adhesion of the secondary gill lamellae. Hepatic sections of S. rivulatus fed CLO diet showed mild hepatic vacuolation. Gastric sections of S. rivulatus fed CO diet showed mild granular degenerative changes covering the mucosal and lining epithelium of the gastric glands. It was concluded that the tropical fish nursery farmers should analyze the feed to ensure the HUFA level. Moreover, the biofloc system may be considered a promising system for tropical marine fish during the nursery phase.