Effect of Gonadal Maturation on the Proximate Composition: A Case Study on the Nile tilapia and African Catfish in Burullus Wetland, Egypt

The current study focused on the Nile tilapia (Oreochromis niloticus) and the African catfish (Clarias gariepinus) in Burullus Wetland. It aimed to investigate the stages of sexual maturity and their effect on the biochemical components of muscle tissue (the edible part) by obtaining 410 individuals with a length range of 8-25cm for the Nile tilapia and 132 individuals with a length range of 17-51cm for the African catfish. The percentage of each maturity stage varied significantly according to seasons (t-test, P<0.05) for both species. The advanced stages of maturity reached the highest mean percentages during summer, followed by spring, and the extended presence of the advanced stages makes both species have a prolonged spawning season. The mean values of the gonadosomatic index (GSI) varied significantly between seasons, and both species peaked during the summer season, indicating a period of intense activity. The values of the biochemical components of the muscles differed significantly according to whether seasonal mean values of GSI or even maturity stages. By engaging in the reproductive activity, a highly significant correlation was observed between the biochemical components of muscle and sexual development, represented by the GSI value. This correlation was positive for moisture content and negative for the rest of the components.