Cyprinodontiformes is an order of ray-finned fish, comprising mostly small, freshwater fish. Many popular aquarium fish, such as killifish and live-bearers, are included. They are closely related to the Atheriniformes and are occasionally included with them. A colloquial term for the order as a whole is toothcarps, though they are not actually close relatives of the true carps – the latter belong to the superorder Ostariophysi, while the toothcarps are Acanthopterygii.
The archerfish or Toxotidae are a monotypic family of perciform tropical fish known for their unique predation technique of "shooting down" land-based insects and other small prey with jets of water spit from their specialized mouths. The family is small, consisting of ten species in a single genus, Toxotes. Most archerfish live in freshwater streams, ponds and wetlands, but two or three species are euryhaline, inhabiting both fresh and brackish water habitats such as estuaries and mangroves. They can be found from India, Bangladesh and Sri Lanka, through Southeast Asia, to Melanesia and Northern Australia.
Telescopefish are small, deep-sea aulopiform fish comprising the small family Giganturidae. The two known species are within the genus Gigantura. Though rarely captured, they are found in cold, deep tropical to subtropical waters worldwide.
Barreleyes, also known as spook fish, are small deep-sea argentiniform fish comprising the family Opisthoproctidae found in tropical-to-temperate waters of the Atlantic, Pacific, and Indian Oceans.
Anablepidae is a family of fishes which live in brackish and freshwater habitats from southern Mexico to southern South America. There are three genera with sixteen species: the four-eyed fishes, the onesided livebearers and the white-eye, Oxyzygonectes dovii. Fish of this family eat mostly insects and other invertebrates.
Jenynsia is a genus of freshwater fishes in the family Anablepidae. Like Anableps species, they are onesided livebearers: some sources indicate that they only mate on one side, right-"handed" males with left-"handed" females and vice versa. However, other sources dispute this. These South American fish are viviparous.
Carinotetraodon irrubesco, known commonly as the red-tail dwarf puffer, is a freshwater pufferfish found only in the lower Banyuasin basin in South Sumatra and the Sambas River in West Kalimantan.
The moonlight gourami, also known as the moonbeam gourami, is a labyrinth fish of the family Osphronemidae native to Indochina. This peaceful species is a popular aquarium fish.
The tentacled flathead, also known as the Indian Ocean crocodilefish, Madagascar flathead or longhead flathead, is a species of marine ray-finned fish belonging to the family Platycephalidae, the flatheads. This species is in the western Indian Ocean, including the Red Sea and the Mediterranean, having invaded as a Lessepsian migrant through the Suez Canal. It is the only species in the monotypic genus Papilloculiceps.
Pseudotocinclus is a genus of armored catfishes native to South America.
Breitensteinia is a genus of catfishes of the family Akysidae. It includes three species.
Samaridae is a family of crested flounders, small flatfishes native to the Indo-Pacific. The family contains four genera with a total of 29 species.
Anableps anableps, the largescale four-eyes, is a species of four-eyed fish found in fresh and brackish waters of northern South America and Trinidad. This species grows to a length of 30 centimetres (12 in) TL. This fish can occasionally be found in the aquarium trade. The fish does not actually have four eyes, but instead each eye is split into two lobes by a horizontal band of tissue, each lobe with its own pupil and separate vision. This allows the fish to see above and below the surface of the water at the same time.
The Siamese tigerfish, also known as the Siamese tiger perch, is a species of ray-finned fish belonging to the family Lobotidae, the tripletails and tiger perches. This fish is endemic to Indochina and is assessed as Critically Endangered by the IUCN.
Vision is an important sensory system for most species of fish. Fish eyes are similar to the eyes of terrestrial vertebrates like birds and mammals, but have a more spherical lens. Birds and mammals normally adjust focus by changing the shape of their lens, but fish normally adjust focus by moving the lens closer to or further from the retina. Fish retinas generally have both rod cells and cone cells, and most species have colour vision. Some fish can see ultraviolet and some are sensitive to polarised light.
The pike topminnow, more commonly known as pike killifish and sometimes referred to as topminnow, is a species of poeciliid found from Mexico to Nicaragua. It has also been introduced to Florida, USA. It is the only known member of its genus. The pike topminnow was described in 1860 by Austrian ichthyologist Rudolf Kner, who gave the type locality as Belize, which is reflected in this species' specific name.
Carlhubbsia is a genus of poeciliids native to Guatemala and Mexico. The name of this genus honours the American ichthyologist Carl Leavitt Hubbs (1894-1979) who originally named the genus Allophallus, a name which was preoccupied by a genus of Diptera.
Boesemania is a monospecific genus of freshwater fish in the family Sciaenidae. This genus contains the single species Boesemania microlepis. Also known as the Boeseman croaker and smallscale croaker, this fish lives in southeast Asian rivers.
The Pacific four-eyed fish is a species of four-eyed fish native to the coastal waters on the Pacific side of southern Mexico to Nicaragua. This fish is gregarious and inhabits mangrove swamps, tidal mudflats, and other coastal brackish ecosystems. During low tide, they will crawl onto shore to eat algae and other organic matter. This species has female biased sexual dimorphism, with males growing to 22 cm TL while females can grow up to 34 cm TL. The male also has a prominent gonopodium 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.
The finescaled four-eyed fish is a species of four-eyed fish found in coastal waters of the Atlantic Ocean from Trinidad and Tobago down to southeastern Brazil. They mostly inhabit brackish environments such as estuaries, mangrove swamps, and tidal mudflats. It grows to approximately 30 cm (12 in) in length.
