2-methylisoborneol implicated as a cause of off-flavour in channel catfish, Ictalums punctatus (Rafinesque), from commercial culture ponds in Mississippi

Abstract

. Samples of water, sediment and fish were collected from six commercial channel catfish, Ictalurus punctalus (Rafinesque), ponds from May to October and analysed for muddy-odour producing compounds. Three episodes of off-flavour in the fish occurred in late summer. The episodes were of 2–3 months' duration and correlated with the levels of 2-methylisoborneol in water, sediment and fish. Oscillatoria agardliii was the dominant phytoplankton in ponds with off-flavour fish. Other known muddy odour-producing compounds such as geosmin, 2-isopropyl-3-mcthoxypyrazinc, 2-isobutyl-3-methoxypyrazine and 2-isobutyl-6-methoxypyrazinc were not detected in the water sediment or at concentrations greater than 5·0 ng/l.