MYOLIQUEFACTION POSTMORTEM (MILKY FLESH) DUE TO KUDOA-THYRSITES (GILCHRIST) (MYXOSPOREA, MULTIVALVULIDA) IN MAHI-MAHI, CORYPHAENA-HIPPURUS L

Myoliquefaction occurred post-mortem in wild and cultured mahi mahi, Coryphaena hippurus L., stored on ice, and the flesh disintegrated upon cooking. The condition was associated with multifocal infection of muscle with Kudoa thyrsites (Gilchrist). Histiolysis is presumably due to enzymes excreted by the parasite, including collagenases, as the collagen fibres of the intermyotomal connective tissues were ruptured and hypochromatic. Myofibre changes were limited to hyaline degeneration and loss of myofibrillar detail. Kudoa thyrsites occurs commonly in Australian populations of the type host species. Thyrsites atun (Euphrasen), which represent a partly sympatric reservoir of infection for C. hippurus. The successful culture of C. hippurus may require selection of disease-free sites or use of filtered water supplies.