Co-infection of Yellowtip Halfbeak Fish (Hemiramphus marginatus) with Isopod and Copepod Parasites from the Coromandal Coast, India

Parasitic fish diseases constitute one of the most important problems in fisheries sector. Among fish parasites, cymothoids are obligatory parasites, in­ festing mostly commercially important fishes. They are protandric hermaphrodites and blood suckers, living on the skin, gill filaments, or in the mouth of the fishes. These parasites retard growth and cause emaciation followed by death. Pathological conditions resulting from parasitic diseases assume high magnitude of epidemics under crowded and other unnatural conditions among fish.Isopod para­ site of the family Cymothoidae under order Beloniformes have been reported from about 350 fish species and over 80% of these occurrence are from tropical and subtropical seas, majority being from the Indo-Malaysian archipelago (Lester, 1995). They are blood-feeding and ectoparasitic on marine, freshwater and brackishwater fish. Their life cycle involves only one host (holoxenic cycle) (Trilles, 1994). Such parasitic isopods are usually large in size, producing serious deleterious effects on the host fishes (Trilles & Hipeau-Jacquotte, 1996).