Differential Role of Dietary Fatty Acids on Gonadal Recrudescence in the African Catfish <i>Clarias gariepinus</i> (Bloch.)

Abstract

Freshwater African male catfish Clarias gariepinus were maintained under oil rich diets differing in fatty acid contents for six weeks during the pre-spawning phase. The diet was supplemented with linseed oil (rich in C18:3 n-3 linolenic acid) or sunflower oil (rich in C18:2 n-6 linoleic acid) or coconut oil (rich in C12:0 dodecanoic acid) (5% w/w each). Gonadosomatic index (GSI) was recorded and, plasma levels of testosterone (T), tri and tetra-iodothyronin (T3 and T4), total lipids, triglycerides, phospholipids and total cholesterol were estimated. GSI was significantly high in linseed oil fed group as compared to other groups, whereas it was significantly low in coconut oil fed group. Plasma levels of T as well as T3 followed the same pattern whereas, change in the T4 level was significant only in fish fed with coconut oil rich diet. Plasma total lipid content was significantly high in response to fatty acids feeding. Level of phospholipid was elevated in the fish fed with linseed oil supplemented diet whereas declined in group maintained under coconut oil rich feed. Total cholesterol was higher in both n-3 and n-6 fatty acids maintained groups with no change in the saturated fatty acid fed fishes. Results indicated that short chain n-3 fatty acid was gonado-stimulatory, whereas saturated fatty acid was inhibitory. Short chain n-6 fatty acid had no impact on the gonadal activity in this catfish during the prespawing phase of the reproductive cycle.