PHABSIM is one of the most famous methods to estimate condition of fish habitat. Recently many researches are performed to improve PHABSIM. In this study we derived the criteria for habitat of Japanese dace (Tribolodon hakonensis). At first, we paid attention to the seasonal change of Japanese dace's habitat. Japanese dace utilized a different area in each season, but the local condition of depth and velocity was approximately constant all the year round. So we clarified that the neig hboring condition affects the condition of fish habitat. Next, we evaluated the effect of morphological changes on the fish habitat, and we clarified that flattening of sand bars and local incisions of riverbed cause the degradation of fish habitat. So we improved original PHABSIM to estimate the morphological impacts, and suggested the new suitability criteria of Japanese dace based on rapid-pool conditions.