Growth Pattern, Diet and Tropical Niche Breadth of the Nile Silver Catfish, Schilbe mystus (Linne 1758) in Asejire Lake, Southwestern, Nigeria

Schilbe mystus is a valued endemic fish species in the Nigerian freshwater, with great potential for culture. Nevertheless, controlled rearing is currently rare due to the lack of knowledge on its food and feeding habits besides other factors. Therefore, growth, food and feeding habits of S. mystus in Asejire Lake were investigated for six months (July to December 2018). A total of 105 specimens (86.00±14.30 g) were collected from fishers. Samples were sexed and grouped according to sizes. Length-weight relationships (LWR) and condition factors were assessed using standard procedures. Gut contents and niche breadth (Bi) were analyzed and quantified using a standard approach. In addition, qualitative and quantitative variations in diet were determined according to sex, size and seasons. Data were analyzed using descriptive statistics, chi-square and multiple linear regressions. The LWR indicated negative allometry growth with ‘b’ value of 2.87 and coefficient of determination (R²) of 0.85. The condition factor of S. mystus was 1.32±0.26, sex ratio of 1:1.23 (♂: ♀) with size distribution ranged from 9.40 cm to 29.70 cm. Dietary analysis showed that S. mystus is a europhagous feeder and a benthic omnivore. Insects, crustaceans and planktons constituted the major food items. Furthermore, significant differences in feeding habits of S. mystus occurred according to sex, size and seasons. The Bi value was high (2.15), indicating a trophic generalist. Hence, this research was conducted to provide key information necessary for the formulation of artificial diet for S. mystus under captivity.