Sheepshead Minnow (Cyprinodon variegatus)

Sheepshead minnows are generally about 1.8 inches (4.6 cm); the largest on record was 3.7 inches (9.3 cm). Their distinguishing characteristics include silver, tubby bodies, one dorsal (back) and one anal fin (fin closest to tail), and no lateral line.
Life History

This fish can live in water so shallow that it may be the only species there. They can survive in water that has been deprived of oxygen by gulping air at the water's surface. Sheepshead minnows are also referred to as variegated minnows, sheepshead killifish, sheepshead pupfish, broad killifish and chubby. In one laboratory study, a single female sheepshead minnow produced 1,028 eggs over a 28-day period. The eggs are adhesive and stick to plants, the bay bottom and to each other.

The sheepshead minnow reaches sexual maturity at three months old. In colder water, spawning occurs February through October; in warm waters, spawning can last throughout the year. Males construct nest pits in bay bottoms to attract females. When mating, males turn bright blue, fiercely defending their nests. Females can spawn several times during the spawning season at 1-7 day intervals, depositing between 100 to 300 eggs per spawning period. Eggs incubate from 4 to 12 days, depending on water temperature. Larvae (young fish) have a total length of 0.16 inches (4 mm) when hatched and are yellowish in color. Hatching typically occurs during spring and summer. Their lifespan is unknown.

Sheepshead minnows dig into sediment to hide from predators or seek refuge from very warm or cold water. Sometimes, they hide in seagrass or algae. They travel in schools, especially when they have been frightened. Predators include red drum, spotted seatrout, Atlantic croaker, turtles and some wading birds. Sheepshead minnows are an important link in the coastal food chain. Their diet consists of plant material, algae, detritus (decomposing dead/animal matter), mosquitoes and smaller fish.

Sheepshead minnows are euryhaline (they can be found in freshwater as well as saltwater). They prefer quiet, shallow waters and have been found in saltwater bays and estuaries, as well as coastal inland areas such as creeks, canals and ditches.
This minnow is found along the Atlantic Coast and the Gulf of Mexico and south along the South American coastline.
Sheepshead minnows are used by humans in a variety of ways. Some fisherman use them as bait, collectors keep them in saltwater aquariums as pets, and the Environmental Protection Agency studies sheepshead minnows to determine pollution levels in certain bodies of water.