en Stock assessment Stock assessment پژوهشي Orginal research papers The study investigated the stomach contents of Indian mackerel (<em>Rastrelliger kanagurta</em>) from the southern part of Qeshm Island in the Persian Gulf from April 2016 through March 2017. The food and feeding behavior of <em>R.</em> <em>kanagurta</em> with a fork length of 17.8 to 22.5 cm was assessed from the analysis of gut contents. The frequency of occurrence and numeric methods were used for stomach content analysis. <em>R. kanagurta</em> fed on diatoms, dinoflagellates, crustaceans, molluscs, forams and ciliates. Organisms of plant origin including diatoms (Bacillariophyceae) and dinoflagellates (Dinophyceae) were the main prey constituting about 72% of food items by number and 66.67% by the occurrence. <em>Coscinodiscus</em> sp. were found to be the most preferable food of plant origin constituting 46.92% by number and 12.88% by occurrence, followed by <em>Guinardia</em> sp. which constituted 9.74% and 7.58% by number and occurrence, respectively. Among zooplankton, crustaceans were the dominant prey contributing to 19.58% of the food items by number and 24.61% by occurrence. Copepoda was the most preferable crustacean constituting 7.57% by occurrence and 5.72% by number. Gastro-Somatic Index (<em>GaSI</em>) was found to be the highest in autumn and the least in winter that is before and after the spawning season. The stomach emptiness index was 36.15% indicating the comparatively gluttonous behavior of the fish. Overall <em>R. kanagurta</em> in the southern part of Qeshm Island in the Persian Gulf is planktonivorous and feeds on a wide range of planktonic organisms. Indian mackerel, Feeding habit, Stomach contents, Frequency of occurrence, Numerical method, Persian Gulf. 563 573 http://jifro.ir/browse.php?a_code=A-10-175-2&slc_lang=en&sid=1 M. Hakimelahi hakimelahi@inio.ac.ir 100319475328460033861 100319475328460033861 Yes Department of Marine Biology, Faculty of Marine Science and Oceanography, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran. A. Savari savari32@yahoo.com 100319475328460033862 100319475328460033862 No Department of Marine Biology, Faculty of Marine Science and Oceanography, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran. B. Doustshenas babakdoust@yahoo.com 100319475328460033863 100319475328460033863 No Department of Marine Biology, Faculty of Marine Science and Oceanography, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran. M. Ghodrati Shojaei shojaeimgh@gmail.com 100319475328460033864 100319475328460033864 No Department of Marine Biology, Faculty of Marine Sciences, Tarbiat Modares University, Noor, Mazandaran, Iran. K.A. Lewis 100319475328460033865 100319475328460033865 No Department of Biology, St. Mary's College of Maryland, St. Mary's City, Maryland, USA.