Cynodontidae fishes or dogteeth tetra

Tetra

thumb|right|250px|Pristella tetra — [[Pristella maxillaris]].thumb|right|250px|Golden Pristella tetra, a [[morph |morph]] of [[Pristella maxillaris]].thumb|right|250px|[[Silvertip tetra]] — Hasemania nana....

s, are a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of 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...

 fishes found in the Neotropics. This group is not very diverse, and includes only five genera

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 and 14 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

. Most of what is known about this family is from the members of the subfamily Cynodontinae

Cynodontinae

Cynodontinae is a subfamily of tropical South American fish of the order Characiformes. They are characterized by an oblique mouth and very distinct canines. They are not prized as food fish, but are important in subsistence and commercial fisheries. Hydrolycus are game fish, having been recently...

, which includes the largest species of this family, up to 65 centimetres (26 in). Understanding of the members of subfamily Roestinae are less known, though they only reach up to 20 cm.

Physical characteristics

They have a very peculiar shape, and their name derives from their elongated and well-developed canines

Canine tooth

In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed teeth...

 which they mainly use to eat other fish. Their pectoral fins are also expanded. The maximum length reached is 65 cm.

Distribution and habitat

These fish live in mid to surface waters of rivers, lakes, and flooded forests. Most species of this family originate from the Orinoco

Orinoco

The Orinoco is one of the longest rivers in South America at . Its drainage basin, sometimes called the Orinoquia, covers , with 76.3% of it in Venezuela and the remainder in Colombia...

 and Amazon basin

Amazon Basin

The Amazon Basin is the part of South America drained by the Amazon River and its tributaries that drains an area of about , or roughly 40 percent of South America. The basin is located in the countries of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, and Venezuela...

. The range reaches as far south as Paraná

Paraná River

The Paraná River is a river in south Central South America, running through Brazil, Paraguay and Argentina for some . It is second in length only to the Amazon River among South American rivers. The name Paraná is an abbreviation of the phrase "para rehe onáva", which comes from the Tupi language...

-Paraguay

Paraguay

Paraguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...

 and Uruguay

Uruguay River

The Uruguay River is a river in South America. It flows from north to south and makes boundary with Brazil, Argentina, and Uruguay, separating some of the Argentine provinces of the Mesopotamia from the other two countries...

 basins and also includes Venezuela

Venezuela

Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...

 and Colombia

Colombia

Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

. Fossil species are also known from Argentina

Argentina

Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

, where they are not found now.

Relationship to humans

Hydrolycus are game fish

Game fish

Game fish are fish pursued for sport by recreational anglers. They can be freshwater or marine fish. Game fish can be eaten after being caught, though increasingly anglers practise catch and release to improve fish populations. Some game fish are also targeted commercially, particularly...

, having been recently added to the International Game Fish Association

International Game Fish Association

The International Game Fish Association is the leading authority on angling pursuits and the keeper of the most current World Record fishing catches by fish categories. Fishermen who are sport fishers are careful to follow their stringent rules for fair play and line requirements in order to...

 in the fly and rod class. Cynodontid fish are also sometimes housed in aquaria

Aquarium

An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...

.