Anisakis simplex (Anisakidae, Nematoda), je nametnik koji parazitira u utrobi morskih riba i sisavaca. Ljudi se najčešće invadiraju parazitom konzumirajući sirovu, blago mariniranu ili soljenu odnosno nedovoljno toplinski obrađenu ribu, glavonošce ili rakove. A. simplex nametnik je brojnih gospodarski značajnih vrsta morskih riba, a među njima i plavoperajne tune (Thunnus thynnus), važnog izvoznog proizvoda, stoga su podaci o njegovoj distribuciji značajni ne samo zbog zdravstvenih već i ekonomskih razloga. Učestalost nalaza i brojnost ličinke III stupnja (invazivnog stadija) nametnika istraživana je na uzorku od ukupno 179 plavoperajnih tuna prikupljenih na uzgajalištima u srednjem Jadranu tijekom tri godine. Nametnik je pronađen u 39 uzoraka ribe a prevalencija je iznosila 21,78% prosječne abundancije 2,69.Anisakis simplex (Anisakidae, nematoda), is the parasite which lives in the guts of marine fish and mammals. Humans can be infested after consumption of raw, slightly marinated or salted and insufficiently cooked fish, cephalopods and crustaceans. A. simplex is the parasite of numerous commercially significant marine fishes, and among them is blue fin tuna (Thunnus thynnus) as an important export product, so the data of its distribution are of great concern for both human health and economic reasons. Prevalence and abundance of the parasite 3rd stage larvae (invading form) was investigated on the sample of 179 blue fin tuna collected from the middle Adriatic marine farms during a period of three years. The parasite was found in 39 samples, with total prevalence of 21.78% and abundance of 2.69, respectively