In the present study, food spectrum of the topmouth gudgeon, Pseudorasbora parva and it food preference to different prey species were investigated in Lake Eğirdir, Turkey. Fish specimens were collected in April, May, June, July and August (2010–2011). Diet analysis was carried out on 88 fish specimens. The benthic larvae of Chironomus sp., the corophiid amphipod Chelicorophium curvispinum and the zooplankter Nitocra hibernica were found to dominate food items. In addition, the fish consumed zooplankton (especially cladocera and copepoda), phytoplankton, annelida, malacostraca and insecta species. Unindentified eggs were also found in the stomachs. Phytoplankton, particularly Gomphonema (V = 0.255, X2 = 13.058, p < 0.01) sp. due to its abundance, was a significant component in the 8.0- to 8.9-cm length sized topmouth gudgeon with distinct preference to the cladocerans Daphnia cucullata (V = 0.191, X2 = 7.331, p < 0.01) and Bosmina longirostris (V = 0.228, X2 = 10.404, p < 0.01), annelids (V = 0.201, X2 = 8.105, p < 0.01) and Trichoptera larvae (V = 0.157, X2 = 4.963, p < 0.01) in 2010 food diet. In return, invasive species topmouth gudgeon is preferable to Cladoceran in the diet of other planktivorous fish (especially Anatolian endemics Aphanius anatoliae type) in Lake Eğirdir. High value of Shannon diversity index was determined in May (H′=1.80) and August (H′=1.70). Fullness index was highest in April, whereas feeding density was lowest in July. Schoener’s indices of diet overlap were estimated between different size classes and months for topmouth gudgeon. The high value of these indices (C = 0.87) indicates that the species principally feeds on the similar in the size classes >8 cm (8.0–8.9 cm, 9.0–9.9 cm, 10.0–10.9 cm, 11.0–11.9 cm).
Part of the book: Selected Studies in Biodiversity