Abstract
Studying the fish composition of small rivers and streams allows us to understand the diversity of species, their ecology, and the interrelationships in the ecosystem. Monitoring of these species can help in assessing the state of aquatic ecosystems and identifying potential problems. This paper shows the results of fish diversity studies of in 12 rivers flowing on the northern slope of the Saur-Tarbagatai Mountains. The study of fish diversity of 12 rivers in 2023 showed the presence of 10 species, representing native and alien ichthyofauna of Kazakhstan. The highest fish diversity was found in the Saryeshki river and the Kendirlik river. Only one fish species is represented in the rivers Zhinishkesu and Sarybulak. The dominant species in numbers are Siberian gudgeon, stone loach, European minnow, Chinese false gudgeon and naked osman. Aboriginal species spined loach is the least represented in all water bodies encountered, and as of 2023 it can be classified as a rare native fish.