The study was conducted to determine growth parameters, mortality, length frequency, age structure and catch per unit effort (CPUE) of Capeota capeota in Hassanloo reservoir in western Azerbaijan. Fish sampling was done seasonally in 2004-2005 by gill net with mesh sizes 20, 30, 40, 50, 60mm.

The results showed age compositions of the fish were 1-5 years old. Average length and weight were estimated at 31.81±0.54cm and 601.30±20.49g, respectively. The range of total length and weight were 19-48cm and 120-1550g. The growth parameters were L"=53.086cm, to= -0.2898, K= 0.4120. Total mortality (Z), natural mortality (M) and fishing mortality (F) were 0.76, 0.58 and 0.18 per year, respectively. Growth in length and weight of Capoeta capoeta population in Hassanloo reservoir compared better than the same age fish in other ecosystems of the region. Average CPUE for 1OOm gill nets in 24 hours was estimated at 11.81kg.