The Arabian Sea meager Argyrosomus heinii (Steindachner, 1907) is an endemic species of the family Sciaenidae, whose geographical distribution range is limited to the Sea of Oman and Arabian Sea. Despite the economic importance of Sciaenidae fishes in other parts of the world, the biology of A. heinii off the Sultanate of Oman is poorly understood and until now there are no publications on their parasites. The present study is the first report of the occurrence of helminthes parasitizing musculature of A. heinii, which were identified as plerocercoids of cestoda belonging to the genus Poecilancistrum Dollfus, 1929 (Trypanorhyncha Diesing, 1863). This study describes infection indices of these parasites, their biological and ecological variations, and distribution of the plerocercoid cysts in the musculature of A. heinii specimens. The study was carried out in the three regions of the Arabian Sea off Southern coasts of the Sultanate of Oman.