Mummichog Mummichog The mummichog ("Fundulus heteroclitus") is a small killifish found along the Atlantic coast of the United States and Canada. Also known as Atlantic killifish, mummies, gudgeons, and mud minnows, these fish inhabit brackish and coastal waters including estuaries and salt marshes. The species is noted for its hardiness and ability to tolerate highly variable salinity, temperature fluctuations from , very low oxygen levels (down to 1 mg/L), and heavily polluted ecosystems. As a result, the mummichog is a popular research subject in embryological, physiological, and toxicological studies. It is also the first fish ever sent to space, aboard Skylab
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