The influence of abiotic factors on fish distribution in Kaulakiai II water reservoir is investigated in present master thesis. Object of research – fish communities of Kaulakiai II water reservoir, situated near Raseiniai. Aim of the research – to estimate the substantial abiotic factors and to evaluate their influence on fish distribution in Kaulakiai II water reservoir. To meet an aim these tasks were set: to estimate the most abundant fish species in reservoir; to estimate and map the structure of the bottom; to evaluate sensual indicators of alive fish during the experimental fishing; to value the quality of water in Kaulakiai II reservoir and to rate it according the standards applied for water quality in carp ponds; to detect peculiarities of fish distribution in water body and to exclude the substantial abiotic factors that have hold on fish distribution in Kaulakiai II (Kybartėliai) reservoir. Methods of research – logical literary analysis, hydro acoustic surveying, written quiz of local anglers, observational studies, mathematical modeling. Results: the Cyprinid fishes (11 species) were the most abundant in Kaulakiai II reservoir fish communities with overall 15 fish species resident. The bottom structure mainly was silt - 83,2 %, sand and oozy sand, respectively 4,6 and 12,2 %. Fish injures, parasites, diseases had no influence on fish distribution in Kaulakiai II reservoir during the research. Low oxygen concentrations were estimated at the bottom of reservoir... [to full text]