Abstract
In order to study the feeding habits and the diet composition of the wide-eyed flounder, Bothus podas (Delaroche, 1809), the stomach contents of 749 specimens, size range 13-24.4 cm in total length (TL), captured from the Gulf of Gabes coasts (south Tunisia, central Mediterranean) were analysed. Examination of the feeding selectivity denotes the studied species as a benthivorous predator fish that focuses on active benthic crustaceans, mainly the isopods Cymodoce truncata, and gammarids. Molluscs, bryozoa and annelids contributed in secondary rank in the diet. Overall, 20.42 % of the stomachs inspected were empty. Little change in the vacuity index (VI) was noticed among size classes and between sexes, but the coefficient showed clear and significant monthly variations. The feeding intensity followed roughly a seasonal trend, with a minimum food intake in winter (% VI = 51.92 in January) and for fishes larger than 21 cm TL. Highest feeding intensity occurred in autumn (% VI = 6.25 in November). Despite the uniform diet composition, seasonal and ontogenetic variations in frequency occurrence were observed for the different prey groups. Seasonal differences appear to be related to the physiological changes during the reproduction cycle of the fish, and influenced by climatic factors in addition to the spatial and temporal abundance of the benthic sources in the study area. The mean weight (Wm/ST) decreased significantly from autumn to summer. The mean number (Nm/ST) was oscillating during the year. Size differences roughly reflect changing food preference with growth and the ability of large individuals to capture larger prey. The mean weight contents increased significantly for adults fishes, while the mean number of prey items did not show important variations among length classes. The obtained results indicated large diet breadth. B. podas makes use of a wide array of prey items and could be considered as an opportunistic predator.