Among the crustacean isopoda there exists ectoparasites which are easy to observe due to their size. They cause lesions on the host that could lead to death. The present study verified the occurrence of parasitic isopods on the fish Serra Spanish mackerel, Scomberomorus brasiliensis (Collette, Russo & Zavala-Camin, 1978) from the coastal waters of Rio Grande do Norte, Brazil. Indices of parasitic infection by isopods were calculated and correlated to the body size, weight and the stage of gonadal maturity of the host. Livoneca redmanni (Leach, 1818) (Cymothoidae) and Rocinela signata (Schioedte & Meinert, 1879) (Aegidae) were registered for the first time in the coastal waters of Rio Grande do Norte. L. redmanni was encountered both in the oral cavity and in the gill chambers of the host, whereas R. signata was found only in the gill chambers. Parasitic isopods were encountered on 31% of S. brasiliensis captured, wherein 86% was L. redmanni and 14% was R. signata. The maximum parasitic intensity was four with a minimum of one isopods per host. The isopods showed a preference for immature and maturing stages of the host S. brasiliensis.
Gill chamber; isopod marine; oral cavity; parasites; parasitic infection
