ICHTHYOFAUNA OF "BOLSHAYA KOKSHAGA" NATURE RESERVE
A comparative analysis of the ichthyofauna in various waterbodies of the «Bolshaya Kokshaga» nature reserve (the Bolshaya Kokshaga river and its backwater, the Arya river, lake Shusher, and lake Kosheer) was carried out. Brief description on biology and ecology of some fish species was given. As a result of the carried out research, 18 fish species were determined to live in the waters of the reserve. Roach is the dominant in the waters, but perch is also widespread. There are more fish species in the Bolshaya Kokshaga river. The farther a body of water is located from the Bolshaya Kokshaga river, the less fish species live in it. Ecological conditions in the Bolshaya Kokshaga river, and lake Shusher in particular, are not favourable for ichthyofauna. Low evenness of ichthyofauna structure is the proof of the idea. Lake Shusher fish was found to have some anatomical abnormalities.