Understanding of nutrition and propagation relationship is one of the key factors affecting aquaculture industry. Hence forward, traditional aquaculture approach is no longer sufficient to achieve the production goals. Analysis of gonadal structure of catfish Clarias gariepinus males and females during their reproductive cycle is the first step to clarify their reproductive biology and improving propagation of this species in Egyptian hatcheries. The nutritional and histological studies revealed that, the relation between protein and energy levels (protein energy ratio), had a crucial influence on the reproductive criteria of African catfish. It also has an effect on other parameters such as growth rate, specific growth rate, feed conversion ratio, protein efficiency ratio and protein productive value.