1. An ecological survey of the fresh water fish in the Samsan River and the Gusan River in Heanam Gun was under taken over a period of 4 days from August 14∼17, 1972, at 8 stations as shown in Fig. 1. 2. The author has collected 702 individuals of 17 species of fresh water fish which belong 16 genus and 9 families, if 4 species heard from the inhabitants at the studied area are added to the number it becomes 21 species. 3. The dominant species in the studied area were Zacco temmincki at station 1, 4 and 8; Carassius carassius at station 2, 3 and 7; Moroco oxycephalus at station 5. The author noticed that the dominant species in the treeless such as station 4 and 8 Moroco oxycephalus stream is replace by Zacco temmincki compared with the case of the stream covered with a forest. 4. The author also noticed that over 200,000 of Anguilla japonica are captured by fishermen per year and over 0.2 per squre meter of Plecoglossus altivelis are observed in 1 km² long at st. 1. 5. The author considered that the small size of 0, 2 or 3 year old fish population in Zacco temmincki, Carassius carassius and Moroco oxycephalus compared with 1 year old group of those species is due to incompleted collection methods and over fishing. 6. The fish fauna of the Daeheung Temple Valley, is quite different campared with, those of the Gucheondong, Muju. The common species in both area are only 7 as shown in Table 5. Rhinogohius brunnes is found in the former only and Gonoprokopterus mylodon, Pseudogobio esocinus, Pseudopungtungia nigra, Moroco sp., Coreoleucisus splendidus, Zacco platypus, Gobiobotia brevebarba, Microphysogohio coreensis, Parasilurus microdorsalis, Pseudobagrus emarginatus, Coreoperca herzi, Mogurnda obscura and Cottus poecilopterus are found in the latter only. 7. The facts of the finding of Pseudoperilampus suigensis and unexistence of Zacco platypus in studied area are very important to study fresh water fish distribution in Korea.