The
mummichog (
Fundulus heteroclitus) is a small
killifish found along the Atlantic coast of the
United States and
Canada. Also known as
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 in 1973.