Bucktooth tetra

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Bucktooth tetra
Bucktoothed Tetra.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Characidae
Subfamily: Exodontinae
Genus: Exodon
J. P. Müller & Troschel, 1844 [2]
Species:
E. paradoxus
Binomial name
Exodon paradoxus
J. P. Müller & Troschel, 1844 [3]
Synonyms [3]

The bucktooth tetra (Exodon paradoxus) is a species of freshwater ray-finned fish, a characin, belonging to the family Characidae. This fish is found in South America. It is the only species in the monospecific genus Exodon. The bucktooth tetra occasionally turns up in the aquarium trade.

Contents

Taxonomy

The bucktooth tetra was first formally described, as Exodon paradocus, in 1844 by the German zoologists Johannes Peter Müller and Franz Hermann Troschel with its type locality given as the Essequibo River in Guyana. [3] When Müller and Troschel described this species they classified it in a new monospecific genus, Exodon. [2] This genus is classified in the subfamily Exodontinae, the toothy or lepidophagous characins, [4] , of which it is the type genus, [5] which belongs to the family Characidae [2] of the suborder Characoidei of the order Characiformes. [6]

Etymology

The bucktooth tetra is the only species in the genus Exodon, this name combines exo, meaning "outer" or "external", with odon meaing tooth, referring to the teeth projecting out. The specific name, paradoxus, means "strange" or "against expectations", also thought to be a reference to the teeth projecting outwards. [4]

Description

The bucktooth tetra has an elongated , laterally compressed body and a forked caudal fin [7] and attains a maximum maximum standard length of 7.5 cm (3.0 in). [8] There is a black line which extends from the operculum to the caudal peduncle [7] and this joins two black blotches, one near the middle of the body and the other near the caudal peduncle. The background colour is iridescent silver which can flash green, yellow or red, with yellow, orange-tipped fins. This species has larger teeth, albeit they do not live up to the species' common name, but the lips are serrated than most characins and they have well developed jaws equipped with pointed, they are cuspid outward projecting pointed tips, an adaptation for their preferred food, the scales of other fishes. [9]

Distribution and habitat

The bucktooth tetra is found in South America where it has a wide but rather disjunct distribution. It has been recorded from the Araguaia -Tocantins, Orinoco, Río Branco, and upper Essequibo River basins in Brazil, Colombia, Guyana and Venezuela. It is normally found in shallow, sandy bottomed areas of rivers, as well as at rapids. [1]

Biology

The bucktooth tetra is a shoaling fish which is mainly lepidophagous, feeding on the scales of other fishes, with fish sampled from the wild having 88% of their diet made up of fish scales, 10% of insects and other animal matter and a tiny amount of plant material. The scale feeding habit has led these fishes to develop handedness. Each fish always approached their intended victim from a favoured side, left handed, or mouthed, fishes attack the right hand side of the fish, biting off scales and then veering towards the fishes tail, right handed fishes attack their victims on their left sides. As they approach the attacked fish they tilt their heads towards that fish. When feeding on larger food items, a shoal of these fish can form a feeding ball as each fish dashes to the food item in the centre of tehs shoal to bite off a piece of the food. [10] The bucktooth tetra is oviparous, following fertilisation the females scatters the eggs on the substrate and they hatch into fry after 2-3 days. [11]

Utilisation

The bucktooth tetra is uncommon in the aquarium trade, [1] because of its scale-eating habits it is not considered an appropraite species for community tanks. In the areas where this occurs this species is used by local people to clean dishes, dirty pots and pans, cutlery and crockery are placed in the river and the shoeals of bucktooth tetra feed on the food remnants and clean the utensils, forming a "feeding frenzy" around the dirty dishes . [10] [11]

Conservation status

The bucktooth tetra is assessed to be Least Concern by the International Union for Conservation of Nature because it has a wide distribution and is common throughout that distribution. [1]

See also

References

  1. 1 2 3 4 Lima, F. (2023). "Exodon paradoxus". IUCN Red List of Threatened Species . 2023 e.T162749267A162749271. doi: 10.2305/IUCN.UK.2023-1.RLTS.T162749267A162749271.en . Retrieved 30 September 2025.
  2. 1 2 3 Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Genera in the family Exodontinae". Catalog of Fishes . California Academy of Sciences . Retrieved 30 September 2025.
  3. 1 2 3 Eschmeyer, William N.; Fricke, Ron & van der Laan, Richard (eds.). "Species in the genus Exodon". Catalog of Fishes . California Academy of Sciences . Retrieved 30 September 2025.
  4. 1 2 Christopher Scharpf (15 October 2024). "Family CHARACIDAE: Subfamily EXODONTINAE Fowler 1958 (Toothy or Lepidophagous Characins)". The ETYFish Project Fish Name Etymology Database. Christopher Scharpf. Retrieved 29 September 2025.
  5. Richard van der Laan; William N. Eschmeyer & Ronald Fricke (2014). "Family-group names of recent fishes". Zootaxa. 3882 (2): 1–230. doi: 10.11646/zootaxa.3882.1.1 . PMID   25543675.
  6. Richard van der Laan & Ronald Fricke (eds.). "Eschmeyer's Catalog of Fishes Classification". Eschmeyer's Catalog of Fishes . California Academy of Sciences . Retrieved 30 September 2025.
  7. 1 2 "Bucktoothed Tetra Exodon paradoxus". tropicalfreshwaterfish.com. Retrieved 1 October 2025.
  8. Froese, Rainer; Pauly, Daniel (eds.). "Exodon paradoxus". FishBase . April 2025 version.
  9. Seth Gibson. "One Tough Tetra: Exodon paradoxus". Tropical Fish Hobbyist Magazine. Retrieved 30 September 2025.
  10. 1 2 "Predators: The Bucktooth tetra". Practical Fishkeeping. Retrieved 30 September 2025.
  11. 1 2 "Exodon paradoxus Bucktooth Tetra". Seriously Fish. Retrieved 30 September 2025.