Native to Newfoundland.
Found in brackish (salty) waters, usually, in saltmarsh flats, estuaries and tidal areas, especially where vegetation is submerged. Mummichogs are very tolerant of a wide range of salinities and temperature.
Widely distributed along the Canadian Atlantic coast and south to the U.S.
Mummichogs are surface feeders, feeding on algae, mollusks, crustaceans and vegetation such as eel grass.
Grow up to five inches long.
Spawning occurs in spring and summer, but temperature significantly affects commencement and duration. Males are active and very aggressive during courtship, but females also attract males by turning on their sides near the bottom and flicking their tails.
No nest is prepared, and pairs of males and females swim about with females slightly above and ahead of males. A spawning male will crowd a ripe female against a solid object (usually a rock), his whole body in contact with hers, head to head, tail to tail. Using his large dorsal and pelvic fins as claspers, the male holds the female tightly. Both begin to quiver and eggs and sperm are released. Up to 460 eggs have been taken from a single female. Released eggs are sticky and attach to substrate. Eggs will hatch on average in 24 days if water temperatures are between 12.8oC to 17.2oC.