STUDIES ON TRIBUTYL TIN CONTAMINATION IN FISH CULTURED IN FRESH-WATER

Tributyl tin compounds (TBT) have been mainly used as an antifouling paint for hulls and fishing nets in marine farms, and they are now known to be marine contaminants. TBT were detected in fish cultured in fresh water in our past survey and hence, TBT in fish cultured in fresh water was analysed and the cause of TBT contamination investigated. Among 25 samples of commercial fish cultured in fresh water (eel, rainbow trout, sweetfish) examined, TBT were detected in 21 samples (84.0%) at the levels of 0.03-0.20-mu-g/g. Consequently, it was suspected that many kinds of fish cultured in fresh water might be contaminated with TBT. In order to investigate the cause of TBT contamination, each 3 samples of rainbow trout, 1 sample of water and 10 samples of feed in 5 fisheries in Saitama Prefecture were examined. TBT were detected in 13 fish samples and all feed samples. The feeds consist of fish meal, flour, rice bran, oil cake of soy bean, etc., and the TBT contamination in the above fishes might be caused by fish meal in the feed.