Two species of righteye flounders, Limanda herzensteini (173~243mm in length) and L. yokohamae (211~271mm in length), were reared under various water temperature conditions, and the effects of temperature on daily feeding rate and their survival were examined. Although L. herzensteini did not feed at temperatures below 0.7℃, no deaths were observed at the lowest rearing temperature (-0.9~-1.3℃). L. yokohamae could also tolerate long-term exposure (approximately three weeks) to subzero temperatures (up to-0.5℃), but they ceased to feed at 1.6~1.9℃. At temperatures below 18~19℃, the daily Feeding rate (%wet body weight per day) of L. herzensteini increased with increasing temperature and began to decrease remarkably at about 19℃, while in L. yokohamae the temperature at when the daily feeding rate began to decrease was about 25℃. In addition, heat resistance experiments suggested that the upper lethal limits of temperature of L. herzensteini and L. yokohamae lay in 25~26℃ and 28~30℃, respectively. From these results, it Became evident that the thermal resistance of these two species which often occur sympatrically in the coastal waters of Japan differs considerably, that is, L. herzensteini is superior in cold resistance, but is inferior in heat resistance to L. yokohamae