First report of Ichthyophonus disease in wild and cultured sea bass Dicentrarchus labrax from the Spanish Mediterranean area

Abstract

Microscopical examination of fresh smears and thin sections of different organs from wild and cultured sea bass Dicentrarchus labrax, collected in the Spanish Mediterranean area, revealed the presence of the 'fungus' Ichthyophonus sp. Prevalence was higher for cultured fish (24.4 %) than for wild ones (14 %). A seasonal pattern of infection. which seemed to be related to temperature, was evident for wild and cultured sea bass. Infection levels increased with host age and were higher for males. Well-vascularised organs were the most frequently infected. Endospores, resting spores, and germinating spores were observed. Granulomas (with intense fibrotic reactions that encapsulated the parasite], involving macrophages, fibrocytes, and eosinophilic granular cells, were the most common lesions seen. This first report of Ichthyophonus sp. In sea bass confirms the importance of the disease in marine fish, especially under culture conditions.