Abstract: We investigated the distribution and elimination rules of methylene blue and its metabolites in allogynogenetic crucian carps (Carassius auratus gibelio) which were raised in aquariums after 0.5-hour bath treatment of 15 mg · L^-1 methylene blue. The concentrations of methylene blue and its metabolites in the main tissues were simultaneously detected by HPLC. The data were analyzed using pharmacokinetics software DAS 3.0.5.The results show that peak concentrations of methylene blue, azure B and azure A were 143.436 μg · L^-1, 110.770 μg · L^-1and 8.444 μg · L^-1 at 0.083^th hour, 0.5^th hour and 8^th hour, respectively. Four kinds of tissue concentrations of methylene blue, azrue B and azrue A from high to low were hepatopancreas, kidney, muscle and skin. Methylene blue, azrue B and azrue A were likely to accumulate in muscle and skin, which still could be detected until 64^th day. Azrue C was not detected in tissues of allogynogenetic crucian carp.