This study investigated the occurrence of metazoan parasites of the parrot-fish, Sparisoma frondosum (Osteichthyes: Scaridae), captured from the coastal waters of Natal, Rio Grande do Norte, Brazil. Using traps and motorized boats a total of 104 fish specimens were captured and their total length, body mass and gonad maturity stages were recorded. The fish samples were necropsied and the parasites encountered were carefully removed and quantified. The isopod Rocinela signata (Isopoda: Aegidae) parasitized 33.91% of fish, with a prevalence of 37.5%, a mean intensity of 2.58 and a mean abundance of 0.97 parasites per fish sampled. The site of parasitic infestation was the gill chambers of the hosts. This is the first record of R. signata parasitizing S. frondosum from the coast of Rio Grande do Norte, Brazil.
