Estimating trophic levels of fishes plays an important role in shedding light on the trophic interactions in aquatic ecosystems. In this short review, available literature data were collected regarding feeding habits of fishes from Hirfanli Reservoir, and the fractional trophic levels (TROPHs) were estimated. Following this, the applicability of functional trophic groups (FTG) proposed for marine fishes was tested for freshwater species. Finally, an attempt to draw a general scheme of the trophic guilds of fish species in the reservoir was made. The literature review yielded information on stomach content data of eight native species, and their TROPHs were estimated on the basis of 86 datasets, provided by nine papers. The calculated TROPH values ranged from 2.00 +/- 0.00 to 4.50 +/- 0.80. The number of cases from which TROPH values are estimated clustered within each of the previously defined FTGs as substantially skewed towards herbivory. The results obtained are a useful tool for applying ecosystem models and management applications for freshwater ecosystems. This work also clearly indicated the need for defining FTG for freshwater fishes that could be different from the marine ones. Such approaches are a solid basis for the maintenance of future conservation planning, especially in reservoirs.