Effects of exercise and temperature on geosmin excretion by European eel (Anguilla anguilla)

Fish raised in land-based aquaculture systems may bio-concentrate geosmin, a lipophilic organic compound produced by microbiota. The presence of geosmin in fish products causes an earthy or musty off-flavour which human consumers do not appreciate and this poses one of the most significant economic problems for land-based aquaculture. To avoid economic damage resulting from market entrance of off-flavoured fish, fish farmers utilize the reversibility of geosmin bio-concentration to depurate the off-flavours from their fish crops. To this end fish are kept in water free of geosmin just before harvest. This procedure, however, is not always sufficiently effective and it is costly as it requires time, effort and use of specific facilities. Therefore better understanding of factors enhancing the geosmin excretion is needed to be able to improve the off-flavour depuration process. This study established that forced exercise during off-flavour depuration increases the rate at which European eel eliminates geosmin from its body. Forcing fish to swim during off-flavour depuration shortens the required depuration time. This finding is relevant for the aquaculture industries confronted with off-flavoured fish crops.