Food items and general conditions of Hyperopisus bebe occidentalis (Lacepede, 1803) caught in Warri River, Nigeria

摘要

Knowledge of the food items consumed by the fish enables farmers have a clear understanding of the fish' dietary requirement so that feeds could be compounded as supplementary alternatives in aquaculture. Food items when consumed in sufficient amount aid optimal growth in fish species. The food items identified in the gut of Hyperopisus bebe occidentalis, in their decreasing order of abundance are as follows: Bacillariophyta> Dinoflagellates> Crustaceans> Chlorophyta among others. Navicula spp contributed the highest percentage (8.5%) while the least percentage (2%) was contributed by Coscinodiscus spp, analyzed by numerical method. Amongst the Dinoflagellates; Gomyaulax spp contributed the highest food item by the point method, while the least was contributed by Ceratium spp (3.5%). Also, the occurrence of Closterium spp was the highest (6%) while Spirogyra spp. recorded the least percentage (3%) both by the frequency of occurrence method. A total number of 202 specimens, comprising 75 female and 127 male specimens of this species were caught from Warri River. This gave a 1:1.7 female to male sex ratio. The total length range measurement for male specimens was 189.2 to 355.0 mm while that for female was 246.0 to 379.0 mm. A body weight range of 50.0 to 499.0 g was recorded for male specimens, while that recorded for female specimens was 106.0 to 400.0 g. Length-weight relationship revealed significant differences (P<0.05) with an 'r' value of 0.77 for male and 0.51 for female specimens. The slope of regression co-efficient 'b' was (2.68) for males and (1.76) for females. Both values were less than 3 implying that the fish increased more in total length than in body weight. The condition index was more favourable to male (4.64) than female (4.14) specimens based on mean value calculated on fresh and gutted body weights in both sexes