1. An ecological survey of the fresh-water fish in the So-Koem-Kang valley and the Wul-Jeong Temple valley area (Fig. 1) was undertaken over a period of 5 day`s from September 16∼20, 1971. 2. The authors collected 6 species of fish in the So-Koem-Kang valley, 9 in the upper stream area of the Yunkokk River, 6 in the Wul-Jeong Temple Valley, 2 in the Ho-Rhung valley, 7 in the Chinkokae valley and 9 in the Yu-Chun 2 Ri stream. 3. The authors considered that the poor fish fauna in the So-Koem-Kang valley and the Wul-Jeong Temple valley originated from the destruction of adjacent forest and the use of a poison drug in fishing. The dominant species are Moroco lagowakii in tne former and Moroco sp. Uchida in the latter. If the studied areas are returned to their original state there should be 12 species of fish in cluding Oncorhynchus macrostomus in the So-Koem-Kang valley and 14 species of fish including Bracymzystax lenok in the Wul-Jeong Temple valley, as shown in Table 7. 4. The difference of the fish fauna on the east and west sides of the Taebaik Mountain Chain is so great that, of 21 species of fresh water fish found in the two areas, only 5 species are common to both; Cobitis taenia, Misgurnus anguillicadatus. Barkatula soni, Anguilla japonica and Cottus poecilopterus. 5. When the studied areas are given satisfactory conservation, can get an accurate basis for studying the so-called "east and west phenomenon" in the distribution of fresh water fish in the Taebaik Mountain Chain region.