Cyprinodontiformes

Cyprinodontiformes; Temporal range: Late Paleocene–recent PreꞒ Ꞓ O S D C P T J K Pg N
	Mummichog, Fundulus heteroclitus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Clade:	Ovalentaria
Order:	Cyprinodontiformes; L. S. Berg, 1940
Type species
	Cyprinodon variegatus; Lacépède, 1803
Suborders
	Aplocheiloidei; Cyprinodontoidei

Cyprinodontiformes is an order of fishes. These freshwater fish are sometimes called toothcarps, though they are not related to the Cypriniformes. While cyprinids are Ostariophysi, toothcarps are Ovalentaria or Acanthopterygii.

Description

Toothcarps are usually small fish. The channels and pores of the lateral line are mainly in the head, while in the body the lateral line is a series of pointed scales.

Many members of the family Cyprinodontidae (the pupfishes) eat plant material as well and some have adapted to a diet very high in algae to the point where one, the American Flag Fish, is a renowned algae eater in the aquarium, in spite of belonging to an order of fishes that do not generally consume any plant material.

In addition, killifish derive some of the carotenoids and other chemicals required to make their body pigments from pollen grains on the surface of and in the gut of insects they eat from the surface of the water; this can be simulated in culture by the use of special color enhancing foods that contain these compounds.

The largest species is the Pacific four-eyed fish (Anableps dowei), which measures 34 cm (13 in) in length,^[1] while the smallest one, the least killifish (Heterandria formosa), is just 8 mm (0.31 in) long as an adult.^[2]

Distribution

They are found in freshwater or brackish environments in America, Africa and Asia. The members of this order are notable for their ability to tolerate environment such as saltwater. They usually live near the surface, taking advantage of areas with oxygen-rich water.

Systematics

Classification

The families in the following classification^[3] are divided according to their modes of reproduction into three main groups:

Viviparous and ovoviviparous, with species that give birth to live offspring.
Oviparous, with species that reproduce through eggs.

Classification based on Eschmeyer's Catalog of Fishes (2025):^[3]

Cyprinodontiformes

Suborder Aplocheiloidei (all oviparous)
- Family Aplocheilidae - Asian killifishes
- Family Nothobranchiidae - African killifishes
- Family †Kenyaichthyidae (Miocene of Kenya)^[4]
- Family Rivulidae - New World killifishes
Suborder Cyprinodontoidei
- Family Pantanodontidae - spine killifishes (oviparous)
- Family Fundulidae - topminnows (oviparous)
- Family Cyprinodontidae - pupfishes (oviparous)
- Family Profundulidae - Middle American killifishes (oviparous)
- Family Goodeidae - splitfins or goodeids (largely viviparous)
- Family Fluviphylacidae - American lampeyes (oviparous)
- Family Anablepidae - four-eyed fish (largely ovoviviparous)
- Family Poeciliidae - livebearers (viviparous)
- Family Aphaniidae - Oriental killifishes (oviparous)
- Family Valenciidae - Valencia toothcarps (oviparous)
- Family Procatopodidae - African lampeyes (oviparous)