Rapid morphological changes in fish larvae during growth make adult classification criteria ineffective for identifying larval fishes. Therefore, species identification of fish larvae requires understanding morphological changes during growth stages within and between species. However, for many fish larvae, the lack of morphological trait information, along with physical damage or protein degradation that occurs during specimen collection and preservation in the wild, creates obstacles for morphology-based identification. A fish larva (10.0 mm SL) collected from the coastal waters of the western Korean Peninsula in August 2019 exhibited morphological characteristics and melanophore distribution patterns closely matching those of an unidentified species of the family Platycephalidae (sp.5). Its MT-CO1 amplicon sequences identified it as Cociella crocodilus, through genetic similarity with MT-CO1 reference sequences and phylogenetic analyses of related species. This study provides significant insights into the early life stages of Cociella crocodilus, marking the first identification of this species at the larval stage.