Optimum Levels of Essential Fatty Acids for Growth and Feed Conversion of Hybrid clarias Catfish (Clarias macrocephalus x Clarias gariepinus)

Abstract

Hybrid Clarias catfish (Clarias macrocephalus x Clarias gariepinus) with individual weight of 0.47 g were kept in 18, 80L glass aquaria at a stocking rate of 20 fish per aquarium. Three replicates of fish were fed each of six isonitrogenous (40%) and isocaloric diets (3.2 kcal/g) containing ω6 and ω3 essential fatty acids (EFA) at inclusion levels of 0/0, 0/2.0, 0.5/1.5, 1.0/1.0, 1.5/0.5 and 2.0/0 g/g (diets 1-6 respectively). The diets were fed to satiation twice daily for 12 weeks to the fish for the determination of optimum levels of EFA for growth and feed conversion of hybrid Clarias catfish. It was shown that hybrid Clarias catfish requrie both ω6 and ω3 EFA  for growth and efficient feed conversion (FCR). The optimun level of EFA in the diet are range from 1.0-1.6% for ω6 and 0.8-0.9% for ω3  (diet 4 and 5). At these level, the fish gained  4,000-4,400% of initial weight with FCR of 1.6-17. Fish fed diet 1,2,3 and 6 gained  less weight (2,900-3,160%) and had poorer FCR (1.9-2.1) than those fed diets 4 and 5 (p<0.05). EFA had no effect on mortality of fed various diets within the period of the study.