Mummichog in 1973. The genus name "Fundulus" comes from "", meaning bottom, from the fish's habit of swimming near muddy bottoms. The species name "heteroclitus" means irregular or unusual. The type specimen was first described by Carl Linnaeus in 1766, from near Charleston, South Carolina. Other scientific names now considered synonyms for this species include "Cobitis heteroclita", "Fundulus fasciatus", "Fundulus pisculentus", and "Fundulus nigrofasciatus". The mummichog belongs to the order Cyprinodontiformes, and the family Fundulidae. There are two subspecies: "F. h. heteroclitus" (Linnaeus, 1766), in the south and "F. h. macrolepidotus" (Walbaum, 1792) in the north. The name mummichog is derived
Mummichog most tolerant of salinity changes (euryhaline). Mummichog larvae can grow in salinities ranging from 0.4 to 100 parts per thousand, the latter being about three times the normal salinity of seawater. Adult mummichogs tolerate low oxygen levels down to 1 mg/L, at which they resort to aquatic surface respiration (breathing in the surface layer of water, richer in oxygen because of contact with air) to survive. They can even survive for a few hours in moist air outside of water, breathing air directly. Populations have developed resistance to methylmercury, kepone, dioxins, polychlorinated biphenyl, and polyaromatic hydrocarbons. One study has looked