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 morphological differences. and genomic Further, eggs of the northern subspecies have filaments (adhesive chorionic fibrils) that eggs of the southern subspecies lack. While the northern subspecies deposits eggs in the sand, the southern subspecies often deposits eggs inside empty mussel shells. The mummichog is very similar to the banded killifish, "Fundulus diaphanus", and indeed the two species have been known to interbreed. The two species may overlap in their choice of habitat, but in general the banded killifish is more commonly found in freshwater, which is not the case for the mummichog. The banded killifish tends to have thin dark