Distribution of the Indo–Pacific eel, Anguilla marmorata, and habitat water temperatures in Oita Prefecture were investigated using literature review, sample surveys, field sampling, and temperature logging. Thirteen records from nine localities were confirmed by literature and voucher specimens. Field sampling revealed the current distribution of the species at eight localities. Winter water temperatures at spring-fed stations where A. marmorata was present differed significantly from those at stations where A. marmorata was absent, the former being higher. Accordingly, over-wintering under the substrate in warmer water temperatures is likely to contribute significantly to the survival of A. marmorata at the northern limit of its range.