بومشناسی آبزیان (Dec 2019)
Feeding Ecology and Natural Feeding Indices of Ghare-Aghaj carp, Cyprinion tenuiradius Heckel, 1847 in the Firoozabad River, Fars Province
Abstract
In this study, the feeding relations of Ghare-Aghaj carp, Cyprinion tenuiradius with microalgae community, and its natural feeding indices were investigated in Firuzabad River (Fars Province), A number of 39 samples were taken monthly during September-December 2017. Samples were fixed in 4% formaldehyde in the site, measured for length and mass, and dissected. Their visceral mass was weighted.،The alimentary tube was isolated, and the intestinal length and weight (including contents) were weighted. Intestinal contents were diluted and observed on counting slides, sorted, and identified. Upon the measurements, feeding indices including gastro-somatic (GI), condition factor (K), fullness (IF), cavity volume (CV), and relative length of gut (RLG) were calculated. Ranges of the total length and weight of the samples were 4.4-13.0 cm and 0.93-25.00 g, respectively. Calculations of the feeding indices revealed that GI, K, IF, and CV were 23.64, 1.07, 1399.70, and 7.69, respectively, which indicate the high intensity of feeding, high fatness (good life conditions), full stomachs, and high voraciousness in this fish. The mean relative length of the gut was 4.40, indicating the herbivory nature of this species. No macrophyte tissues were recognized in the gut content, but most of the contents were comprised of microalgae of genera Navicula, Cymbella, Diatoma, Pinnularia, Gomphonema, and Cosmarium, and very few numbers of Cymatopleura, Caloneis, Nitzschia, Spirogyra, and Pediastrum. Amounts of mud and unidentified sediments were also observed in the gut, which seems to have been unintentionally eaten through feeding. Based on the only source of food recognized in their gut, it can be concluded that C. tenuiradius has a phytoplanktivorous feeding regime in Firoozabad River under current conditions.
