Fish otoliths, a crystal form of calcium carbonate (Popper & Lu, 2000), are detected in the inner ear of fish (Campana, 2004; Schulz-Mirbach et al., 2010). Otoliths have been used for classification, age identification, growth rate, migrant behavior, and certain fish habitat (Tsukamoto & Kajihara, 1987; Rodríguez Mendoza, 2006). Otolith is typical for species (Popper et al., 2005), and plays an important role in hearing and balancing as mechanoreceptor (Popper et al., 2005; Rodríguez Mendoza, 2006). In this study, both otolith morphometric and morphology of Butis koilomatodon were analyzed to understand deeply the role of otolith in the growth and development of this fish. Butis koilomatodon (Bleeker, 1849) (Perciformes: Butidae) is one of three goby species of the genus Butis (Froese & Pauly, 2021). The species B. koilomatodon dwells ARTICLE INFO