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Cyprinodon variegatus
Sheepshead Minnow
Synonym(s):
Class: Actinopterygii
Order: Cyprinodontiformes
Family: Cyprinodontidae
Photographer: Fishes of North Carolina
Source: http://www.ncfishes.com
Description
The Sheepshead Minnow is a smaller fish (1.8-3.5 in.), silver in color with yellow tints on the underside of the fish and olive green above. It has one dorsal and one anal fin with no lateral line; the pectoral fins are large in relation to the rest of the body. During the breeding season, males become very colorful with steel blue, bright green and salmon-pink colors. A female minnow is picture above
Ecological Threat: As opposed to competition for food or habitat, this species poses a reproductive threat to native Cyprinodon species. While it does provide some competition for habitat, it primarily threatens them through hybridization (crossing of two species). The sheepshead minnow is able to breed with native species of the Cyprinodon genus, which can cause the two species to merge into one species, favoring the sheepshead minnow and eliminating already endangered native Cyprinodon species. Hybridization events can lower the biodiversity in a habitat and affect food web structure.
Biology: They are a hardy species that can survive in very shallow and oxygen-deprived salt or freshwaters. After three months, the sheepshead minnow reaches sexual maturity, and spawning events can happen from February through October. Females can spawn numerous times during the season and can release up to 300 eggs per spawning period. After 4-12 days, the eggs hatch into larvae.
History: It was first reported from Lake Balmorhea in the 1960s, with blame focusing on bait-bucket releases. It appeared in Leon Creek by the 1970s and the Pecos River proper by the early 1980s.
U.S. Habitat: The Sheepshead minnow can tolerate freshwater and saltwater, and prefer shallow waters. They can be found in creeks, canals, saltwater bays and estuaries.
Distribution
Native Origin: Atlantic Coast, Gulf of Mexico, and along the coastline of South America.
TEXAS: Native to Brazos River drainage system and estuarine waters along the Gulf of Mexico.
U.S. Present: Atlantic Coast, Gulf of Mexico,
Distribution in Texas: Native to Brazos River drainage system and estuarine waters along the Gulf of Mexico.
Considered invasive to the Pecos River, Lake Balmorhea and Leon Creek.
SIMILAR SPECIES
Comanche springs pupfish (Cyprinodon elegans), Pecos pupfish (C. pecosensis) and Leon Springs pupfish (C. bovinus).
Management
Management often focuses on the aquarium trade and advising owners to avoid releasing loricariids is paramount in curbing the invasion. By being a responsible pet owner you can prevent the spread of these pests in our Texas freshwater systems. Follow this link to learn about alternatives to dumping your tank when you no longer want your aquarium pets.
Biologists working in Harris County started aggressive fishing strategies in Buffalo and Brays Bayous in 2016 but the current status of these efforts is unknown (2020). There have also been control efforts in the San Marcos and Comal rivers under the Edwards Aquifer Habitat Conservation Plan.
Text References
Echelle, A.A. and Echelle, A.F., 1997. Genetic Introgression of Endemic Taxa by Non‐natives: A Case Study with Leon Springs Pupfish and Sheepshead Minnow: Introgresión Genética de Taxas Endémicos Debido a Especies No‐nativas: Un Caso de Estudio del Pez Cachorro de Leon Springs y el Pez Bolín. Conservation Biology, 11(1), pp.153-161
Kennedy, S.E.1977. Life history of the Leon Springs pupfish, Cyprinodon bovinus. Copeia 1977(1):93-1
Stevenson, M.M. and T.M. Buchanan. 1973. An analysis of hybridization between the cyprinodont fishes Cyprinodon variegatus and Cyprinodon elegans. Copeia 1973(4):682-692.
Wilde, G.R., and A.A. Echelle. 1997. Morphological variation in intergrade pupfish populations from the Pecos River, Texas, USA. Journal of Fish Biology 50(3):523-539.
Online References
https://tpwd.texas.gov/huntwild/wild/species/sheepsheadminnow/
https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=662
http://txmarspecies.tamug.edu/fishdetails.cfm?scinameID=Cyprinodon%20variegatus
SEARCh Online
Google Search: Cyprinodon variegatus
Google Images: Cyprinodon variegatus
NatureServe Explorer: Cyprinodon variegatus
Bugwood Network Images: Cyprinodon variegatus
