Marine leech (Zeylanicobdella arugamensis) infestation in cultured orange-spotted grouper, Epinephelus coioides

Abstract

Heavy infestation of a marine leech occurred among tank-reared juvenile and adult orange-spotted grouper, Epinephelus coioides Hamilton, at SEAFDEC AQD, Philippines with a prevalence of 83% and 17%, respectively. The leeches were attached in large numbers on the fins, lower jaw, under the operculum, eyes, and inside the mouth of the fish. The attachment and feeding sites exhibited frayed fins, hemorrhages and swelling of the host's skin. External and internal features indicate that the leech is Zeylanicobdella arugamensis De Silva (Hirudinea, Piscicolidae). The parasite can be effectively controlled using 50 ppm formalin bath treatment for 1 h.