Milt-egg ratio in artificial fertilization of the Asian freshwater catfish,Clarias macrocephalus, injected salmon gonadotropin-releasing hormone analogue and domperidone

Abstract

Catfish Clarias macrocephalus are artificially fertilized by inducing females to spawn using various hormones (Mollah and Tan, 1983; Ngamvongchon et al., 1988; Thalathiah et al., 1988; Tan-Fermin, 1992; Tan-Fermin and Emata, 1993). However, the necessity of administering hormones to males and the quantity of eggs that can be effectively fertilized per unit volume of milt have not been investigated in these studies. In catfish, males need to be sacrificed because milt cannot be stripped by pressing the abdomen of the fish. Sacrificing male catfish to obtain the milt can cause further depletion of the wild population of C. macrocephalus. A standard procedure maximizing the use of available gametes to ensure the maximum effectiveness of artificial fertilization may contribute to the development of a breeding programme for re-stocking catfish in the natural habitat.