Abstract: Four isozymes(EST, CAT, LDH and MDH) in seven tissues(gill, heart, hepatopancreas, intestines,
kidney, muscle, brain and eye) of Sinibotia reevesaeand S. superciliaris were comparatively studied using the method of poly- acrylamide gel electrophoresis. The results showed that, 1. It was found that there exist six esterase isozyme bands, two cata- lase isozyme bands, four lactate dehydrogenase isozyme bands, eight malate dehydrogenase isozyme bands; 2. Each isozyme displays an apparent unique tissue-specific property in seven tissues of the two fishes and is closely related to its physiological function; 3. There were similarities and differences between the four isozyme bands of two Sinibotia genus of fishes. The grea- ter similarity was found in EST-1 and EST-2 isozyme expression between S. reevesae and S. superciliaris. The expression of CAT isozyme in hepatopancreas and kidney of two Sinibotia genus fishes was stronger than in other tissues. The expression of LDH isozyme was relatively simple in terms of zymogram. The expression of mitochondrial MDH isozyme was found to dis- play a rather huge difference in the same tissues of S. reevesaeand S. superciliaris.