We examined the effect of binary coded wire tagging on oxygen consumption rates of seven species of seawater fish and three species of freshwater fish. Nine were found that one hour after tagging, the oxygen consumption rates of tagged fish were 50-80% higher than those of non-tagged controls. The oxygen consumption rates of Girella melanichty, Oreochromis mossambicus and Carassius auratus returned to the original level six to seven days after tagging. Additionally, no effect was found on both growth and mortality rates in a long term observation.