Studies on aspects of the biology of Tilapia mariae (Boulenger, 1899) (Osteichthyes Cichlidae) in Ethiope River, Niger Delta, Nigeria

Aspect of the biology ofTilapia mariae Boulenger, 1899, in Ethiope River were examined. T. mariae was captured in the river throughout the year and constituted about 31% of the cichlid catch. It attained a standard length of 17.5 cm; 19.7 cm total length with a weight of 148 g and showed preference for zones with a silty sand substratum. The growth in length relative to weight was isometric. The condition factor ranged from 2.8 to 4.2 and fluctuated with individual fish size. k-values were slightly higher in the females and during the wet season. T. mariae fed predominantly on algae, detritus and aquatic macrophytes, with allochthonous and benthic invertebrates complementing their diets. Food items consumed also varied with fish size and season. Breeding occurred throughout the year and fecundity ranged from 280–560 eggs per female. About 0.69–4.73% of its body weight was put into egg production.