Aims of this study were to determine the changes of ichthyofauna composition during the ten-year period and to determine the correlation between ichthyofauna composition and water turbidity. I determined the ichthyofauna composition through the qualitative, quantitative, and ecological guilds analysis. The results of qualitative analysis indicate that 12 fish species inhabit the Butoniga reservoir. According to the quantitative analysis results, the biomass and abundance of alborella (Alburnus arborella Bonaparte, 1841), common carp (Cyprinus carpio Linnaeus, 1758), gibel carp (Carassius gibelio Bloch, 1782), pumpkinseed (Lepomis gibbosus Linnaeus, 1758) anditalian chub (Squalius squalus Bonaparte, 1837) decreased. At the same time, the biomass of tench (Tinca tinca Linnaeus, 1758) while the its abundance decreased. Roach (Rutilus rutilus Linnaeus, 1758) and pikeperch (Sander lucioperca Linnaeus, 1758) increased their biomass and abundance, while the northern pike (Esox lucius Linnaeus, 1758) only increased its biomass. Ecological guilds analysis results indicate that the fish who live in the water column, phyto-lithophilous, omnivorous, euritopic and allochthonous species are dominant. I used the linear regression method to determine the correlation between ichthyofauna composition and water turbidity. I chose the bivariate model in which the turbidity is independent variable and proportions of phytophilous, phyto-lithophilous, omnivorous and piscivorous fish are dependent variables. The results of linear regression analysis indicate that the correlation of phytophilous fish proportion is very strong and negative, the correlation of piscivorous fish is strong and negative and the correlation of phyto-lithophilous and omnivorous fish is strong and positive.