Japanese sculpin, C. reinii is endemic to Lake Biwa and its tributaries. There are, however, few information on suitable habitat for respective developmental stage of the spicies.

This study analyzed the distribution pattern and habitat preference of the sculpin in River Wadauchi, a tributary of L.Biwa, Japan, from June 23^rd to November 10^th, 2011, by comparing physical environments (water depth, current velocity and bottom material) in relation to the developmental stages of the spisies.

All of fish avoided the river bottom with deep water depth and bottom of concrete.Small individuals prefered the bottom with fast current velocity and large one selected the bottom with large gravel.

Thus, habitat for Japanese sculpin requires, according to the developmental stage needs requires a variety of current velocity and bottom material in the river.So , homogenization of physical environment in the river by river improvement is great problem in respective developmental stage.