Accumulation of hydroxy lipids in live fish infected with fish diseases

Abstract

Lipid hydroperoxide (LPO) and hydroxy lipid levels of diseased fishes were investigated. Although significant differences in LPO levels were not always observed between normal and diseased fish, hydroxy lipid levels in muscle and liver were significantly higher in diseased fish than in uninfected normal fish cultured with the same feed in the same cage or in wild normal fish. Hydroxy triglyceride levels of diseased yellowtails with streptococcal infection were significantly elevated in ordinary and dark muscle, and especially in the liver; 1072±78 in diseased fish compared to 632±45 (nmol/g tissue) in normal fish cultured with the same feed. In this case, the polyunsaturated fatty acid contents of the diseased fish were decreased. This was notable, especially with respect to the decrease of docosahexaenoic acid. These trends, namely, increased accumulation of hydroxy lipids in the liver of diseased fish and decreased levels of polyunsaturated fatty acids, were observed in sweetfish with ulcer disease, globefish with Heterobothrium okamotoi infection and/or emaciation disease, red sea bream infected with edwardsiellosis and/or Vibrio anguillarum, yellowtail with jaundiced disease, and carp with cold water disease.