Comparative analysis of the heart index Thymallus arcticus of the Kazyr river (r. Yenisey basin)

The article discusses the results of studies of the morphophysiological index of the heart of Thymallus arcticus, which was caught in the Kazyr River (Krasnoyarsk Territory) in the autumn (end of October) 2020. Also presented is a comparative analysis of the heart index for the summer and autumn periods. Attention is paid to the dependence of the value of the indicator on the assessment of the quality of the river and the state of the environment. The information and the location are new to research.