Esox panchax (now assigned to the genus Aplocheilus) was described by Hamilton (1822; p 211) from the ditches and ponds of Bengal (present-day Bangladesh and parts of the state of West Bengal, India). The name A. panchax has been applied to many species of killifishes found across the Indian subcontinent and South-East Asia, but with suggestions that several species are likely to be confused under this name (Kottelat, 2013); and that the distribution of A. panchax sensu stricto, is likely to be restricted to the Gangetic delta and the eastern coastal plains of India (Costa, 2008). However, recent phylogeographic analyses have revealed that A. panchax is widely distributed in South and South-East Asia (Beck et al., 2017; Dahruddin et al., 2017), and comprises of three major mitochondrial clades/lineages (Beck et al., 2017).