ABSTRACT. – The aim of this paper is to describe the diet of the population of Gobius paganellus from the Gulf of Gabes, looking at seasonal and ontogenetic shifts and identifying the main preys. This species is an intertidal fish sparsely distributed on the Tunisian coast. A total of 629 specimens with total lengths ranging from 8.9 to 14.3 cm were captured on the Gulf of Gabes. In the Laboratory, the TL was measured and prey items in the stomach contents were identified to the possible taxonomic groups. Of the total number of stomachs examined, 143 were empty (22.73 %). Rock goby fed mainly on crustaceans; gastropods were secondary preys; teleosts, polychaetes and echinoderms were occasional preys. Significant differences were found between the diets of males and females. Ontogenetic changes in the diet of G. paganellus were apparent. Gastropods importance increased with the increasing goby size. Moreover, a seasonal study of the diet showed significant differences in the contribution of gastropods during certain times of the year. The calculation of trophic level gave an average of 3.43 ± 0.16 for the whole population of G. paganellus of the Gulf of Gabes. Based on the composition of its diet, this species may be considered as an omnivorous fish with a preference for animal prey.