The mummichog is a small species of killifish native to the Atlantic Coast of North America. These small fish inhabit the brackish (slightly salty) areas of the coast including salt marshes and estuaries. They are able to survive in highly polluted river systems that experience significant fluctuations in salinity and remarkably hypoxic (low oxygen) conditions, and therefore are common in industrial areas where other creatures cannot survive. The name “mummichog” is derived from an indigenous word meaning “going in crowds”, a reference to this species’ tendency to swim in large shoals.