Margariscus margarita, the Pearl dace, is a species of cyprinid

Cyprinid

The family Cyprinidae, from the Ancient Greek kyprînos , consists of the carps, the true minnows, and their relatives . Commonly called the carp family or the minnow family, its members are also known as cyprinids...

 fish. It is demersal, freshwater

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 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

Invasive species

"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....

.

Description

Margariscus margarita is a bottom-dwelling freshwater fish that has been recorded to reach sizes of 16 centimetres (6.3 in), however, it does not commonly grow beyond about 9.3 centimetres (3.7 in). 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

Dorsal fin

A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

, anal fin, and pelvic fins. 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

Lateral line

The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...

.

This species is omnivorous: its diet comprises algae as well as arthropods such as chironomids and water fleas. Margariscus margarita spawns

Spawn (biology)

Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

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

Distribution and habitat

Margariscus margarita inhabits North America, in southern Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 and the northern United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. It can be found in the Mississippi River

Mississippi River

The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...

, Hudson Bay

Hudson Bay

Hudson Bay , sometimes called Hudson's Bay, is a large body of saltwater in northeastern Canada. It drains a very large area, about , that includes parts of Ontario, Quebec, Saskatchewan, Alberta, most of Manitoba, southeastern Nunavut, as well as parts of North Dakota, South Dakota, Minnesota,...

, and Great Lakes

Great Lakes

The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...

. M. margarita inhabits lakes, ponds, and rivers, usually over a sandy or gravelly substrate. M. margarita 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

Great Plains

The Great Plains are a broad expanse of flat land, much of it covered in prairie, steppe and grassland, which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S...

" region, having declined since the region's settlement. M. margarita is threatened mainly by habitat destruction

Habitat destruction

Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...

 and alteration, and introduced species

Introduced species

An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

. 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 (fish)

Bass is a name shared by many different species of popular gamefish. The term encompasses both freshwater and marine species. All belong to the large order Perciformes, or perch-like fishes, and in fact the word bass comes from Middle English bars, meaning "perch."-Types of basses:*The temperate...

, pike, or trout

Trout

Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...

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