Journal of Aquatic Ecology

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In this study, trophic interactions were studied among three elasmobranches including Iago omanensis, Rhinobatos punctifer and Torpedo sinuspersici coexisting in the depth ranging from 50 to 100 meters in the Oman Sea (Sistan and Balochistan waters). A total of 238 specimens were collected using industrial bottom trawlers of ‘FERDOWS’ during spring and summer,2014 and their stomach contents were analyzed based on VI, FO, %IRI indices and nMDS analysis. Results showed that I. omanensis fed mainly on teleosts, and crustacean and cephalopod were found in the several stomachs. Moreover, T. sinuspersici had specialized diets on teleosts. On the other hand, R. punctifer had a specialized diet on crustacean. An analysis of similarity showed significant differences among three studied species (R=0.574; P=0.001). Analysis of pair-wise tests detected the greatest dietary differences between R. punctifer and T. sinuspersici, while I. omanensis and T. sinuspersici showed the lowest differences. The results showed that there is resource partitioning, which can be related to morphology and feeding behavior of each species.

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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.

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In light of limited biological data, particularly concerning the dietary habits of four-lined terapon fish (Pelates quadrilineatus), a comprehensive study was conducted. A total of 140 fish samples were gathered from various points along the Makkoran coast, including the Chabahar fish market and catch unloading centers in Chabahar, Ramin, and Tis. The investigation aimed to delineate their seasonal feeding patterns from the onset of summer 2019 until the conclusion of spring 2020. The findings revealed the average total length and weight of the fish to be 18.51±4.13 cm and 82.30±16.71 grams, respectively. Moreover, the average relative length of the intestine and stomach fullness/emptiness stood at 0.52% and 49.29%, respectively, indicating the species' carnivorous nature and moderate feeding tendencies. Notably, gastro-somatic index, feeding intensity, and condition factor during autumn were significantly lower than in other seasons, with averages of 1.48±0.24, 95.34±25.11, and 0.72±0.068, respectively (p<0.05). Assessment of food preference and relative importance unveiled mollusks and crustaceans as primary dietary components, with copepods, polychaetes, and fish identified as secondary sources for this species. Among mollusks and crustaceans, the gastropod and hermit crab held the greatest significance, accounting for 41% and 42% of the P. quadrilineatus' diet, respectively. Overall, the feeding indicators suggest that this species thrives as a carnivorous fish, exhibiting moderate feeding habits and favorable living conditions in the coastal waters of Makkoran

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