Crude Lipid Levels in Semi-Purified Diets for Zebrafish

Zebrafish is a popular vertebrate model with limited knowledge of nutritional requirements and no established standard diets for scientific purposes. The aim of this study was to determine the inclusion range of lipids in semi-purified diets for zebrafish. Five isonitrogenous casein-gelatin based diets were formulated to contain 0.55%, 4.87%, 7.65%, 10.65%, and 13.94% of crude lipid (CL). Zebrafish (initial weight ± 232 mg) were distributed in 3 L aquaria in a recirculating water system in a completely randomized design (n=3). Fish were hand-fed twice daily to apparent satiety for 40 days. Weight gain, feed efficiency, and protein productive value of zebrafish increased signifi-cantly (P < 0.05) as CL increased up to 6.5, 8.3, and 8.6%, respectively, and decreased after this point. Survival of fish fed diets containing 0.55% CL was lower (P<0.05) than that of fish fed diets con-taining 4.87% to 13.94% CL. Body fat and adipocytes diameter of fish increased (P<0.05) increasing dietary CL levels. In conclusion, the ideal lipid level in semi-purified diets for zebrafish is between 6.5% and 8.6% of the diet.