Effects of sublethal levels of tributyltin chloride in a new toxicity test organism: the Chinese rare minnow ( Gobiocypris rarus).

A newly developed toxicity test organism, the Chinese rare minnow ( Gobiocypris rarus), which has similar merits to some common experimental fishes and could become a standardized test species for China, was used in a short-term study with emphasis on accumulation in fish muscles and cytological effects of sublethal concentrations of tri-n-butyltin chloride (TBT). The 1-year-old fish were exposed for 1 or 2 weeks to a concentration range of 50 to 5,000 ng TBT/L in static systems. Hepatosomatic Index (HSI) and Gonad Somatic Index (GSI) sensitively showed the adverse effects of TBT to the fish. Compared with the nominal TBT concentrations in water phase, 459-(5,000 ng TBT/L, 1 week) to 4,065- (50 ng TBT/L, 2 weeks)-fold higher concentrations of butyltin species were detected in the corresponding exposure fish muscle. Contaminations of TBT in muscle tissue increased with both the exposure levels and exposure time. The cellular pathological effects in the liver were studied. These included vacuoles with increasing number and size, swelling of mitochondria, abnormal nuclei, and decreases of rough endoplasmic reticulum cisternaes. The results confirmed that the Chinese rare minnow ( G. rarus) could be utilized as a useful species to evaluate water toxicity in the laboratory.