Elopidae is the most speciose family within the Elopiformes, comprising seven valid species. Despite this reduced number of species, the family presents poorly resolved systematics, mainly owing to its wide distribution and highly conserved anatomic features. Therefore, we aimed to explore the species diversity of the Elopidae using species delimitation, genetic diversity, and phylogenetic analysis combined with DNA barcoding of the COI gene. The results from the delimitation analysis grouped the species into a single cluster, while the genetic diversity analysis among the groups showed a distance ranging between 1.29 and 2.78%. Both phylogenetic and haplotype network analysis grouped the species into four clades, associated with the distribution of the organisms. The lack of resolution in the species delimitation analysis might be directly associated with the recent radiation of the group, a hypothesis corroborated by both the low genetic diversity (close to the 2% threshold) and the few mutations that separate the haplotypes observed among the species. Interestingly, our data supported a new arrangement for the Elops species. In addition, the data available in public databases present taxonomic errors at several levels. Although some issues remain unsolved, our results can be used in the identification of taxa and provide information to assist taxonomic revisions of the Elopidae.