en Biology & physiology Biology & physiology پژوهشي Orginal research papers <a name="OLE_LINK1">The</a> shape diversity among populations of <em>Scartelaos</em><em> tenuis</em> (Day 1876) from five stations (194 specimens) in the Persian Gulf, Strait of Hormuz (Qeshm Island), and the Sea of Oman were investigated. The shape variation was assessed by geometric morphometrics, using 14 morphological landmarks. <a name="OLE_LINK3">The two sexes were not distinguishable by <ins cite="mailto:mobin2" datetime="2018-02-19T20:49">the </ins>shape.</a> <a name="OLE_LINK4">Fish samples <ins cite="mailto:mobin2" datetime="2018-02-19T20:50">were </ins>classified into two distinct groups, the </a>fish from the Persian Gulf (Heleh and Asaluyeh), and the specimens of Qeshm Island and the Sea of Oman (Chahoo, Dargahan and Jask). <a name="OLE_LINK5"></a>The Persian Gulf and the Sea of Oman are characterized by specific environmental parameters of surface waters, including temperature and salinity. The shape discrepancies of <em>Scartelaos tenuis</em> specimens from different stations are probably because of ecological parameters of the Persian Gulf and Sea of Oman. <a name="OLE_LINK6">Our results suggest that the observed pattern of morphological variation is almost some kind of polyphenism induced by distinct environmental factors. </a><br> &nbsp; Geometric morphometrics, Environmental factors, Polyphenism, Scartelaos tenuis, Persian Gulf, Sea of Oman 612 622 http://jifro.ir/browse.php?a_code=A-10-2357-1&slc_lang=en&sid=1 M. Ghanbarifardi Meghfardi@gmail.com 100319475328460033882 100319475328460033882 Yes Department of Biology, Faculty of Sciences, University of Sistan and Baluchestan, Zahedan, Iran M. Aliabadian aliabadian@yahoo.com 100319475328460033883 100319475328460033883 No Department of Biology, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran H.R. Esmaeili hresmaeili22@gmail.com 100319475328460033884 100319475328460033884 No Ichthyology and Molecular Systematics Research Lab., Department of Biology, College of Sciences, Shiraz University, Shiraz 71454, Iran