The authors investigated biochemically and histopathologically spontaneous and experimental methemoglobinemia in the Japanese eel (Anguilla japonica). 1. Spontaneous methemoglobinemia. The disease occurred in Japanese eels reared in culturing ponds using a water recirculating system which had high levels of nitrite (7.8～10.5ppm) in the winter of 1980, in Mie Prefecture. Twelve sampled fish had chocolate brown colored blood and liver characteristically. A few of them were accompanied by dropsy and jaundice. The blood of nine fish had high proportions of methemoglobin to total hemoglobin as 33～70%. Histopathological findings were varied with the levels of methemoglobin. In fish having 61～70% of methemoglobin levels, degeneration of erythrocytes in the blood, erythrophagocytosis in the spleen and thrombosis of gill lamellae were distincitive. In fish having 33～47% of methemoglobin levels, degeneration of erythrocytes was mild and hemosiderosis was intensive in the spleen and the kidney. 2. Experimental methemoglobinemia. Twelve eels were exposed to a nitrite concentration of 20, 30 and 40 ppm, using a flow-through system of aquaria, for 31 days. The fish exhibited methemoglobinemia and had 4～66% of methemoglobin to total hemoglobin. They manifested histopathological characteristics similar to those of fish suffering from spontaneous methemoglobinemia. Based on results from this study, it was judged that nitrite poisoning was a representative cause of methemoglobinemia.
雑誌名
三重大学水産学部研究報告 = Bulletin of the Faculty of Fisheries, Mie University
ニホンウナギのメトヘモグロビン血症
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