We conducted a year-long underwater census to survey fish fauna on a reef off Kurahashi Island in the Seto Inland Sea. A total of 53 species (8 orders, 29 families) were recorded; 16 species were residents, 37 were seasonal residents. No tropical/warm-temperate fish were confirmed. The total number of fish species (41) peaked in September and October, but drastically decreased to just 18 species in January and February because of the disappearance of most seasonal residents. These seasonal residents appeared to be prevented from continuing residence in the central part of the Seto Inland Sea because of the low water temperature in winter.