Mummichog become established on the Atlantic coast of Portugal and southwestern Spain, starting in the 1970s and some have now reached the western Mediterranean basin. There may also be introduced populations in Hawaii and the Philippines. As bait fish, mummichogs are sometimes released in freshwater habitats, where they can survive, and there have been reports of individuals in New Hampshire ponds, as well as the upper Ohio River and Beaver River. The mummichog is a common fish in coastal habitats such as salt marshes, muddy creeks, tidal channels, brackish estuaries, eelgrass or cordgrass beds, and sheltered shorelines. It can be found
Mummichog bars on a light side, whereas in the mummichog the bars are thin and light on a dark side. Internally, the banded killifish has 4-7 gill rakers, as opposed to 8-12 in the mummichog. This species ranges along the Atlantic coast of North America, from Gaspé Peninsula, Anticosti Island and Port au Port Bay in the north to northeastern Florida in the south. It is present on Sable Island, southeast of the closest point of mainland Nova Scotia in the Atlantic Ocean. The approximate geographical division between the two subspecies lies in New Jersey, Delaware and Virginia. Introduced populations have