Otolith shape were investigated to identify two species of genus Dussumieria inhabiting the northern Oman Sea, south of Iran. The main aim of the investigation was to analyze otolith shape differences between these species. The sagittal otoliths of the rainbow sardine Dussumieria acuta Valenciennes, 1847, and the slender rainbow sardine Dussumieria elopsoides Bleeker, 1849, belonging to different length groups were described. The results showed two groups of special characteristics of the sagittal otoliths in D. acuta, and D. elopsoides. The first group is the characteristics that are useful to separate these species from other clupeid species, however these characteristics are closely related to one another in these species of Dussumieria genus. The second group comprises characteristics that vary due to genetically guided mechanisms and biological factors, but that may be useful to define species and are species-specific.