Central mudminnow

The central mudminnow (Umbra limi) is a small fish in the family Umbridae of the order Esociformes. It is found in central and eastern North America in productive waters. It is fairly tolerant of low oxygen concentrations and, as a result, it is sometimes the only, or one of a very few, fish species present in waters susceptible to winter or summer kill.

Habitat

The central mudminnow is carnivorous and typically feeds in the benthic area of freshwater habitats. According to Colgan and Silburt, it prefers amphipods, coleopterans, and anisopterans while avoiding zooplankton and other planktonic species. In a study by Colgan and Silburt, they found that an average of only 0.9% of the contents of dissected stomachs of U. limi contained zooplankton. Chironoids and gastropods, when taken from the dissection, had a combined volume of about 60%, which proves that the mudminnow feeds mainly in benthic areas.

This fish seems to prefer water with low dissolved oxygen levels, warmer temperatures, and low flow. It is able to live in hypoxic conditions because of its ability to breathe air. This species is also known to feed in the winter in temperatures as low as 1.1 °C. According to Jenkins and Miller, some animals that feed on the mudminnow are the grass pickerel, sunfishes, northern pike, and catfishes; it is also preyed upon by birds, foxes, and snakes when caught out of water. This mudminnow is known to bury itself in the mud or sand to avoid capture in some situations. Also, Jenkins and Miller found that the mudminnow is a shoaling fish; they prefer to be with other mudminnows rather than by themselves. This shoaling mechanism seems to reduce their predation risk.

Distribution

Umbra limi is a widely distributed species that inhabits many freshwater systems such as lakes, streams, and wetlands near the littoral zone, or near the shore, and around dense cover in central North America west of the Appalachian Mountains, including the St. Lawrence River, Great Lakes, Hudson Bay, Red River, and the Mississippi River basins from Quebec to Manitoba and south to central Ohio, western Tennessee, and northeastern Arkansas. The central mudminnow has also been introduced into many of the tributaries in Connecticut and Massachusetts. Their habitats being marshy lands and rivers are under attack by human development and contact constantly and is likely causing a decline in their populations.