Effects of reducing dietary lipid levels on growth and body composition of hybrid tilapia in an intensive recirculating-water system

Juvenile hybrids of Mozambique tilapia Oreochromis mossambicus X blue tilapia O. aureus reared in an intensive recirculating-water system were fed isonitrogenous (30% protein), isocaloric (2,870 kcal/kg digestible energy) diets with varying levels of dietary lipids. Diets containing 3, 6, and 8% lipids were fed at a rate of 3% of biomass per day. Fish grew from 68 g to 250 g in 91 d. Specific growth rates and feed efficiency ratios were not significantly different between treatments. Examination of fat levels in fillets and livers did not demonstrate any trend as lipid levels in diets decreased. The amount of fat in the viscera did not decrease with a reduction of lipid in the diets. It was concluded that lower fat levels could be used in feeds for intensive production systems if the caloric value of the diet is balanced with suitable carbohydrates. In addition, fat level in the final fillet product will not be reduced by lowering the dietary fat level in fish feed within the range of 3% to 8% lipid.