All fish / Fundulidae

Diamond killifish

Fundulus xenicus

Also known as diamond killi, adinia xenica, adinia, diamond killifish

This small killifish has a deep, diamond-shaped body, and males carry narrow pale bars over an olive-green to bronze body with turquoise speckling. It comes from salt marshes, lagoons and mangrove pools, so keepers who want a hardy, colourful fish for a brackish tank value it.

Care at a glance

Care level

Moderate

Temperament

Semi

Adult size

4 cm

Temperature

18 to 28 °C

pH

7.5 to 8.5

Smallest tank

60 litres

Keep as

Group of one male to two or more females

Diet

Omnivore: small live and frozen foods such as brine shrimp and bloodworm, plus flakes and some algae or plant matter

Swims

Middle of the tank

Lifespan

2 to 3 years

Water

Brackish

Wild range

Northern Gulf of Mexico coast, USA (southern Florida to Texas)

Breeding

Females scatter eggs among fine plants or spawning mops over several days, and the eggs hatch in about two weeks. Breeding is fairly easy in brackish water, and the fry will take newly hatched brine shrimp straight away.

Good to know

It does poorly in pure fresh water over the long term, so keep it in brackish water. Males can be territorial with each other, so give them space and cover.