All fish / Fundulidae

Gulf killifish

Fundulus grandis

Also known as gulf killifish, bull minnow, mud minnow, cocahoe, cocahoe minnow, gulf killie, bull killifish

A sturdy, thick-bodied killifish from Gulf salt marshes, olive to dark green above with pale spots, while breeding males show bright yellow fins and darker bodies. It tolerates a huge range of salinity and temperature, so it suits unheated brackish or coastal biotope tanks and is widely sold as live bait.

Care at a glance

Care level

Easy

Temperament

Semi

Adult size

12 cm

Temperature

15 to 30 °C

pH

7 to 8.5

Smallest tank

150 litres

Keep as

Group of 5 or more, one male per few females

Diet

Omnivore: pellets, frozen bloodworm, brine shrimp, mysis, small crustaceans and some vegetable matter

Swims

Middle of the tank

Lifespan

3 to 5 years

Water

Brackish

Wild range

Gulf of Mexico coast from Florida to Texas and northeastern Mexico; also Atlantic Florida and Cuba

Breeding

It spawns in spring and summer, scattering adhesive eggs among plants or spawning mops near the surface, often timed with high tides in the wild. Eggs can be removed and kept damp or in shallow water, hatching in about two weeks, and the fry take brine shrimp nauplii readily, so breeding is fairly straightforward.

Good to know

Males become territorial and boisterous in breeding condition and will eat small fish and shrimps. It is easily confused with the closely related mummichog (Fundulus heteroclitus); check local rules before collecting or moving wild fish.