Modern methods for obtaining metaphase plates from the somatic cells of fish, most effective in the study of polyploid species, were selected and tested. The technique with CoCl2 and colchicine treatment is recommended on the basis of empirical data for representatives of the genera Carassius and Cobitis. Th e detailed description of this modified technique and characteristics of metaphase plates of Carassius auratus Linnaeus, 1758, Carassius carassius Linnaeus, 1758 and triploid form of Cobitis taenia Linnaeus, 1758 received under tested method is presented in the paper.
In the rivers of the Northern Ukraine by meams of karyological and allozyme analysys obtained extensive natural hybridization between Cobitis taenia and Sabanejewia aurata, initially leading to the formation of diploid hybrids. Besides that certain water bodies are predominantly populated by triploids of the C. taenia - C. tanaitica - S. aurata biotypes. Since the share of this kind of hybrid biotypes significantly exceeds the number of individuals of S. aurata, it is concluded that the hybridization of a common and eurybiontic C. taenia with rarer stenobiontic S. aurata, is of absorbing character.