Abstract
Shapes of the swim bladders were studied for clarifying differences in three species of the genus Tribolodon, T.hakonensis (Günther), T.taczanowskii (Steindachner) and T.ezoe Okada et Ikeda, taken from several localities in Hokkaido. The feature of the tip of the posterior chamber of the swim bladder, with two types, is useful to distinguish between T.ezoe (round or grainy tip) on the one hand and T. hakonensis and T.taczanowskii (tapering or sharp tip) on the other hand. The length of the posterior chamber of the swim bladder was also different among the three species, i.e., it is longest in T.hakonensis, shortest in T.ezoe, and intermediate in T.taczanowskii.
