author(s)
NJ Mustafayev, Sh. R Ibrahimov, NM Hasanov, Sh. A Veliyev, Kh. M Safarov, GK Ismayilov, TS Khudiyeva, LI Mammadova and GB Mustafayeva

abstract
In 2019-2022, an ichthyological study of six species of the main commercial fish was carried out at the Shamkir reservoir on the Kura River. Studies have shown that the ratio of males and females among the main fish species caught in this reservoir was approximately 1:1 for bream (Abramis brama orientalis), zander (Sander lucioperca) and carp (Cyprinus carpio), 2:3 for Prussian carp (Carassius auratus gibelio), 5:4 for Caspian roach (Rutilus caspicus), and 3:2 for Danubian bleak (Chalcalburnus chalcoides). In all fish species, the difference between the body weight of males and females without viscera was greater than the difference between their total body weight, which was due to the presence of eggs in females. For the same reason, the fullness according to Fulton of males and females more differs, than fullness according to Clark. Comparition of the different age groups shows that the growth speed of lenth and mass of the carp and zander were higher than of the rest fish. The growth rate of roach and Danubian bleak was the lowest compared to other fish.