The Allegheny pearl dace (''Margariscus margarita'') is a species of cyprinid fish. It is

demersal The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of ...

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

fish, with a dark green back and silvery body. This species is omnivorous, consuming algae, as well as arthropods. ''M. margarita'''s range spans southern Canada and the northern United States. While not considered endangered at the federal level in the United States, several states either consider this species endangered or threatened; it faces threats of habitat destruction and

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

Description

''M. margarita'' is a

bottom-dwelling The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning ...

freshwater fish that has been recorded to reach sizes of , however, it does not commonly grow beyond about . The maximum age ''M. margarita'' has been recorded to reach is four years. The body is long with small eyes and mouth. There are eight rays each in the dorsal fin,

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

, and

pelvic fins Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

. The dorsal side is dark green in colour, with silvery flanks and a grey or white ventral side. Between late autumn and summer, males may have a brilliant orange-red stripe on the flanks, below the

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

. This species is omnivorous: its diet comprises algae, as well as arthropods, such as chironomids and

water flea The Diplostraca or Cladocera, commonly known as water fleas, are a superorder of small crustaceans that feed on microscopic chunks of organic matter (excluding some predatory forms). Over 1000 species have been recognised so far, with many more ...

s. ''M. margarita''

spawns Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...

in the spring. This species typically reaches sexual maturity at one year.

Distribution and habitat

This species inhabits North America, in southern Canada and the northern United States. It can be found in the Mississippi River,

Hudson Bay Hudson Bay ( crj, text=ᐐᓂᐯᒄ, translit=Wînipekw; crl, text=ᐐᓂᐹᒄ, translit=Wînipâkw; iu, text=ᑲᖏᖅᓱᐊᓗᒃ ᐃᓗᐊ, translit=Kangiqsualuk ilua or iu, text=ᑕᓯᐅᔭᕐᔪᐊᖅ, translit=Tasiujarjuaq; french: b ...

, and the Great Lakes. ''M. margarita'' inhabits lakes, ponds, and rivers, usually over a sandy or gravelly substrate. It feeds by sight, so waters it inhabits are generally clear streams and bog drainage systems.

Relationship to humans

''Margariscus margarita'' is not considered endangered federally in the United States; however, in several states, it is considered endangered or threatened. The species is uncommon in the

Great Plains The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, an ...

region, having declined since the region's settlement. ''M. margarita'' is threatened mainly by habitat destruction and alteration, and introduced species. Human activities such as reservoir construction, groundwater pumping, stream diversions, and channelization all contribute to the former. The introduction of exotic species such as

bass Bass or Basses may refer to: Fish * Bass (fish), various saltwater and freshwater species Music * Bass (sound), describing low-frequency sound or one of several instruments in the bass range: ** Bass (instrument), including: ** Acoustic bass gui ...

pike Pike, Pikes or The Pike may refer to: Fish * Blue pike or blue walleye, an extinct color morph of the yellow walleye ''Sander vitreus'' * Ctenoluciidae, the "pike characins", some species of which are commonly known as pikes * ''Esox'', genus of ...

, or trout have an especially detrimental effect on this species. ''M. margarita'' is also caught for use as bait, which may contribute to its decline.

References

{{Authority control Margariscus Cyprinid fish of North America Fish described in 1867