Mummichog

The mummichog is a large killifish that lives in schools in the tidal marshes, estuaries and salty channels of North America's Atlantic coast. It can tolerate a very wide range of conditions, from near-freezing water to warm summer waters and from fresh water to seawater; this hardiness has made it a model fish frequently used in environmental and physiological research. In the breeding season males darken, silvery spots and bars appear on their bodies and yellow-orange color on their bellies. Females lay their eggs at the base of marsh grasses and inside empty mussel shells.

• At least 100 liters for a group of 4–6.
• Brackish water: a salinity of roughly a third to a half of seawater is suitable.
• No heater is needed; 15–22°C is ideal, and a cool room temperature is enough.
• A strong filter, sand substrate, rocks and salt-tolerant plants; a tight lid.

Omnivorous and gluttonous. It readily accepts mysis shrimp, bloodworms, brine shrimp and granules; it also consumes algae and plant matter.

An active fish that moves about in schools. In the breeding season males get rough with each other. It hunts small fish and shrimp that fit in its mouth.

Good companions: a group of its own species; sturdy species of its own size suited to brackish water.

Avoid: freshwater community fish (salt and temperature incompatibility), small fish and shrimp.