Sheepshead minnow

Cyprinodon variegatus

FreshwaterFish

Care at a glance

Temperature: 68–81°F (20–27°C)
pH: 7.5–8.5
Adult size: 2.8 in (7 cm)
Minimum tank: 26 gal (100 L)
Temperament: Peaceful
Social behavior: Social
Swim level: Middle
Difficulty: Medium
Breeding: Hard
Rarity: Very rare
Origin: United States, Mexico
Family: Cyprinodontidae

Overview

The sheepshead minnow is a stocky, adaptable pupfish best kept as a group in a hard, alkaline tank with open swimming space. It is generally peaceful, but breeding males turn bright blue and defend territories, so give the group room to spread out. Feed a varied diet of live and frozen foods such as brine shrimp, bloodworms and daphnia, along with algae and vegetable matter, as wild fish graze widely. It stays in the middle and lower water. A tank of 100 liters or larger suits a group, and firm, mineral-rich water keeps it in good health.

In the wild

Sheepshead minnows live along the coasts of the United States and Mexico, in salt marshes, lagoons, estuaries and coastal ditches. They are strongly euryhaline, coping with fresh, brackish and even hypersaline water, though they are kept here in freshwater that is hard and alkaline. Provide a tank with a mineral-rich substrate such as crushed coral to hold the pH high, between about 7.5 and 8.5, with warm water from roughly 20 to 27 C. Sturdy plants, rockwork and clean, well filtered conditions round out the setup.

Good to know

The sheepshead minnow belongs to the pupfish family Cyprinodontidae and grows to about 7 cm, with a deep, chunky body and, on breeding males, an iridescent blue sheen. It is not an annual killifish but a hardy, territorial spawner: males hold small patches of bottom and court passing females, which lay eggs on the substrate and among plants over a long breeding season. Reliable aquarium breeding is rated hard, since it usually calls for hard, saline-leaning water and careful separation of aggressive males.

Did you know

The sheepshead minnow is one of the most salt-tolerant fish known, living everywhere from freshwater ditches to coastal pools several times saltier than the sea, and even surviving brief swings in salinity that would kill most other fish.