Mummichog

Fundulus heteroclitus is native to Atlantic coastal marshes, tidal creeks, and estuaries from Canada to Florida and is famous for its extraordinary physiological adaptability. It has been used extensively in scientific research on salinity adaptation and environmental tolerance. Males develop vivid green-yellow breeding colouration in spring, making them genuinely attractive display fish.

Water: 10–28 °C, pH 7.0–8.5, specific gravity 1.000–1.025; tolerates virtually any salinity. Tank: 80 L minimum; sandy substrate, robust plants or artificial alternatives, light brackish preferred. Feeding: Omnivorous scavenger; accepts flake, pellets, frozen foods, and small live invertebrates. Behaviour: Active, robust schooler; males may chase females; keep in groups with equal sex ratios. Compatibility: Hardy community fish for brackish or cold temperate setups; pairs well with killifish relatives.