This study was conducted on 50 samples of fish, Mullus surmuletus collected from the beach of the city of Sirte – Libya during the period from March to May 2019 , and after dissecting the fish samples using special autopsy tools and examining them well "in the laboratory, the examination showed that 22 fish were infected with some types of parasitic nematodes : 5 fishes were infected with a parasite Anisakis simplex that was collected from the intestine, and 11 of these fishes were infected with a parasite Contracaecum multipapllatium , which was collected from and thus is the most widespread parasite in these fish under study. the results also showed that 6 of these fishes were infected with a parasite Hysterothylacium aduncum , which was collected from the stomach and intestines of these fishes.