First occurrence of Argathona macronema (Bleeker, 1857) (Isopoda: Cirolanidae) on coral reef fishes along the Tuticorin coastal water, Gulf of Mannar.

Isopod Parasites are considered as a major threat to the fishing industry, due to rigorous disease outbreaks. The parasites from the two economically important reef fish family Lutjanidae and Serranidae are analyzed i.e. Epinephelus malabaricus and Lutjanus rivulatus. The samples are obtained from the landings of Trawl net from Gulf of Mannar region of South east coast of India. They are severely infested by the isopod parasite Agrathona macronema in the Pectoral fins and ventral region of the body. This species is found to be the new record in the Gulf of Mannar region and deposited in the Marine laboratory of Kamaraj College. Length and weight of the host and parasites are measured. The parasites infested on 13 specimens of E. malabricus out of 8 and 17 out of 12 species of L. rivulatus. The prevalence of parasite on the grouper and snapper fish (61.53 and 70.58 %) and mean intensity (2.62 and 2.58 %) respectively. The prevalence was maximum in L. rivulatus and minimum in E. malbaricus may be to the host specificity. Further studies are needed to know the life cycle of the parasite, host preference, disease outbreak and its role in the coral reef ecosystem.