ICHTHYOPHONUS INFECTIONS IN CULTURED MARINE FISH FROM SPAIN

Ichthyophonus sp. is reported for the first time in Mugil capito (thin lip grey mullet) and Liza saliens (leaping grey mullet). The fungus wa s also found in L. aurata (golden grey mullet), Dicentrarchus labrax ( sea bass). Sparus aurata (gilthead sea bream) and Scophthalmus maximus (turbot), whereas Mugil cephalus (grey mullet) was not parasitized. I n fish sampled periodically, the highest prevalences were observed in sea bass and the lowest in turbot. Among the fish sampled occasionally , the fungus was found associated to an epizootic in thinlip grey mull et. Ichthyophonus was never found in fish weighing <0.5 g. An increase in the prevalence of infection with the age of turbot and gilthead se a bream was observed. Gilthead sea bream and sea bass showed higher pr evalences in a closed system than in open and semi-intensive systems. Multinucleate spherical spores. hyphae and endospores of Ichthyophonus sp. parasitized different organs of thinlip and leaping grey mullets, though infection intensity was maximal in the spleen. In the remainin g fish, the fungus was found mainly in the trunk kidney, where it appe ared frequently in a necrotic form. Ichthyophonus sp. can be considere d a potential threat for marine fish aquaculture, especially in cultur e conditions which may favour the introduction and transmission of the fungus. (C) 1997 The Fisheries Society and the British Isles.