The Pacific four-eyed fish (''Anableps dowei)'' is a species of

four-eyed fish The four-eyed fishes are a genus, ''Anableps'', of fishes in the family Anablepidae. They have eyes raised above the top of the head and divided in two different parts, so that they can see below and above the water surface at the same time. Lik ...

native to the coastal waters on the Pacific side of southern

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

Nicaragua Nicaragua (; ), officially the Republic of Nicaragua (), is the largest country in Central America, bordered by Honduras to the north, the Caribbean to the east, Costa Rica to the south, and the Pacific Ocean to the west. Managua is the cou ...

. This fish is gregarious and inhabits

mangrove swamps A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in severa ...

, tidal mudflats, and other coastal

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

ecosystems. During low tide, they will crawl onto shore to eat

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

and other organic matter. This species has female biased

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

, with males growing to 22 cm (8.7 in) TL while females can grow up to 34 cm (13.4 in) TL. The male also has a prominent

gonopodium 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 ...

used to impregnate females during mating. As with other members of Anablepinae, this species is livebearing and has left or right leaning genitals to prevent

inbreeding Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and o ...

. The name "four-eyed fish" comes from how the eyes of the fish are split into two lobes horizontally, each with its own pupil and vision. This allows the fish to see above and below the water at the same time.

References

{{Taxonbar, from=Q947767 Anablepidae Viviparous fish Fish of Central America Freshwater fish of Central America Cyprinodontiformes category:Fish described in 1861