Biometry and diet of Perccottus glenii Dybowski, 1877 found in stagnant water nearby Veliko Gradište (northeastern Serbia)

Abstract

The aim of this study was to describe biometric and feeding characteristics of highly in-vasive species Perccottus glenii in the investigated locality. A total of 85 fish were elec-trofished in the drainage channel located at the vicinity of Veliko Gradište (northeastern Serbia) and preserved in the alcohol solution. In the laboratory, fish were measured (TL, ± 0.01 mm; W, ± 0.01 g), otholits and digestive tracts were removed for age determination and dietary analysis (stereomicroscope). Biometric analysis included length-frequency distribution using 10 mm class intervals; determination of average length and weight for each age group; lenght-weigth relationship; Fulton’s condition factor. Ingested organisms were identified to the lowest reliable taxonomic level (mainly order) and counted. The respective ranges of TL and W of examined fish were 35-140.7 mm and 0.5-40 g. Length class 70.1-80.0 mm clearly dominated (24%). Four age groups were determined (0+-3+), and their descriptive statistics is presented. The value of allometric coefficient for the length-weight relationship (b= 3.068) indicated isometric growth. Fulton’s condition fac-tor did not differ between age groups. Empty digestive tract was found in 2 specimens. A total of 12 prey categories representing Ephemeroptera, Trichoptera, Odonata, Hemiptera, Chironomidae, Coleoptera, Gastropoda, Hirudinea, Oligochaeta, Gammaraidae, uniden-tified and terrestrial insects were identified in the diet. Generally, the diet is entirely com-posed of aquatic invertebrates, as only one terrestrial insect was found. Obtained results did not show clear difference in diet composition between age groups. However, analysis have shown that the most diverse diet characterize 2+ age. By frequency, the insect larvae were categories with highest participation regardless of age.