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).