Text Size: A  A  A


Fundulus heteroclitus

The mummichog grows five to six inches long and gathers in schools of hundreds of individuals. (NOAA/Wikimedia Commons)
The mummichog grows five to six inches long and gathers in schools of hundreds of individuals. (NOAA/Wikimedia Commons)

Also known as the mud minnow, the mummichog is a minnow-like killifish found along muddy marshes, tidal creeks and the sheltered shores of the Chesapeake Bay. 


  • Stout-bodied with flattened head, rounded or squared-off tailfin, pointed teeth and a lower lip that juts out beyond the upper one 
  • Grows five to six inches long, with females larger than males
  • Coloration varies with sex; shading can change based on surroundings  
  • Females: brownish green body features 12 to 15 dusky vertical stripes. Dorsal and anal fins tinted green
  • Males: darker than female. Green or olive body features 15 silver vertical stripes. Pectoral, pelvic and anal fins yellow. Blue or orange markings present during spawning season 


  • Found in muddy marshes, tidal creeks and grass flats and along sheltered shores 
  • In summer, may range along a hundred feet of the shoreline and a few yards offshore 
  • During colder months, may retreat to deeper waters or burrow six to eight inches deep in bottom mud or silt 


  • An abundant, permanent resident of the entire Chesapeake Bay
  • Found on the Atlantic coast of North America from Labrador, Canada, to Mexico 


  • Opportunistic feeders eat a range of items, including algae, plants, insects and insect larvae, worms, small crustaceans and mollusks, the eggs of their own species, other fish and carrion 


  • Predators include larger fish, wading birds and seabirds 

Reproduction and Life Cycle:

  • Spawning occurs from April to August, during which time males often exhibit aggressive behavior 
  • Females attract males by displaying their silvery bellies
  • Females can spawn up to 460 eggs eight times in a single season. Females lay sticky eggs in empty mollusk shells or on dead vegetation when the tide is highest during the new or full moon. When tide recedes, eggs are exposed to air. Eggs will not begin to hatch until once again covered with water during the next month's highest tide 
  • When hatched, larvae measure about seven millimeters long 
  • Most adults reach sexual maturity during their second year and live for three years 

Other Facts:

  • "Mummichog" is a Native American word meaning "going in crowds"; mummichogs often form schools of hundreds of individuals 
  • A tolerant species, able to withstand changes in temperature and salinity, low oxygen and pollution
  • Able to consume up to 2,000 mosquito larvae in a single day; have been introduced to ponds and ditches as natural method of mosquito control 
  • Often sold to fishermen as live bait 

Sources and Additional Information:

Click tabs to swap between type and habitat.

410 Severn Avenue / Suite 112
Annapolis, Maryland 21403
Tel: (800) YOUR-BAY / Fax: (410) 267-5777
Directions to the Bay Program Office
Terms of Use | Privacy Policy
©2012 Chesapeake Bay Program | All Rights Reserved