FISH FAUNA OF THE OSTER RIVER BASIN (DESNA RIVER BASIN, UKRAINE) ? RECENT DATA

According to recent data, fish fauna of the Oster River basin numbers 21 species, including two introduced species: Perccottus glenii and Pseudorasbora parva. 17 spe- cies of fish were registered in the lower section of the river (4 of them for the first time), 21 species were found in the middle section (12 of them were not previously noted for this section) and only 11 species were found in the upper section (6 species were not previously noted for this section). Six species ? Pseudorasbora parva, Misgurnus fos? silis, Pungitius platygaster, Gymnocephalus cernua, Babka gymnotrachelus and Protero? rhinus semilunaris ? are recordered in the Oster River for the first time. Fish population of the lower part differs by qualitative composition, primarily due to its link with the Desna River. Only 11 species were registered in three tributaries of the Oster River and in their basins. Nosivochka River has 6 species, including introduced Cyprinus carpio and Hypophthalmichthys molitrix. Five species were recorded in the Divytsia River basin and six species are found in the V’iunnytsia River. The most frequently caught species in the Oster River basin were Leucaspius delineatus and Rhodeus amarus (F = 75.0), Scardinius erythrophthalmus and Tinca tinca (F = 66.7).