The pinktail chalceus (''Chalceus macrolepidotus''),U.S. Fish and Wildlife Service.
Pinktail Chalceus (Chalceus macrolepidotus) Ecological Risk Screening Summary
'. 2018. also called the pinktail characin, is a species of freshwater fish of the family Chalceidae found in South America. It is one of five fish in the genus ''

Chalceus ''Chalceus'' is a genus of fish that inhabits freshwater habitats in South America. Members can be found in the Amazon River, Amazon and Orinoco basins, as well as in the The Guianas, Guianas and various tributaries of the former. It is the sole ...

'', and is the type species of the genus.

Description

The pinktail chalceus is a small, light-colored freshwater fish with a tail that is usually dark red to pink and is much more intensely colored than the rest of the animal. It has large, noticeable scales and reaches 24.5 cm SL, making it the largest known member of ''Chalceus''. The smallest is ''Chalceus epakros''. ''

Chalceus epakros ''Chalceus epakros'' is a species of freshwater fish in the family Chalceidae, found in northern South America. It is a fairly recent addition to its genus, alongside the species '' C. guaporensis'' and '' C. spilogyros''. Description ''Chalc ...

'', before being classified, was regularly misidentified as either the pinktail chalceus or the yellowfin chalceus (''Chalceus erythrurus''). ''C. epakros'' and the pinktail can be told apart because the pinktail is uniform silvery in color, whereas ''C. epakros'' has a line down the middle of either side that reaches its caudal peduncle.

Etymology

The common name "pinktail chalceus" comes from its caudal fin, which is typically much more saturated in color than the main body. The specific name ''macrolepidotus'' means "large scale" in Latin, which is considered an accurate reflection of its scale size; the scales themselves are

cycloid In geometry, a cycloid is the curve traced by a point on a circle as it Rolling, rolls along a Line (geometry), straight line without slipping. A cycloid is a specific form of trochoid and is an example of a roulette (curve), roulette, a curve g ...

. The original description gave it the common name "large-scaled chalceus". The genus name ''Chalceus'' comes from the Greek word ''chalkos'', which means brass or copper. This name was given based on the observation that the scales on the

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

were coppery ("sometimes golden") when preserved in alcohol.

Taxonomy

Upon description by French naturalist

Georges Cuvier Jean Léopold Nicolas Frédéric, baron Cuvier (23 August 1769 – 13 May 1832), known as Georges Cuvier (; ), was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuv ...

in 1818, the pinktail chalceus was placed into the new genus ''Chalceus''. By way of

monotypy In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

, it ended up as the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

therein. Since then, several additions and retractions have occurred, as well as a redescription of the genus in the year 2004, and there are now five accepted species in total, ''C. macrolepidotus'' included. The original scientific name given by Cuvier has remained its accepted scientific name. Synonyms include ''Brycon macrolepidotus'', ''Chalceus ararapeera'', ''Chalceus erythrurus'', ''Pellegrina heterolepsis'', and ''Creagrutus pellegrini''. The name ''Chalceus erythrurus'' has since been assigned to a different species in the genus altogether. The yellowfin chalceus, ''C. erythrurus'', was briefly classified as ''Chalceus macrolepidotus iquitensis'', a subspecies of the pinktail chalceus, by biologist Shoji Nakashima in 1941.

Habitat

The pinktail chalceus is found in well-oxygenated (fast-flowing) waters in South America; specifically, it is found in French Guiana, Guyana, and Suriname, inhabiting the Orinoco and Negro Rivers. ''C. epakros'' and the pinktail are the only two ''Chalceus'' species known to occur in

Guyana Guyana, officially the Co-operative Republic of Guyana, is a country on the northern coast of South America, part of the historic British West Indies. entry "Guyana" Georgetown, Guyana, Georgetown is the capital of Guyana and is also the co ...

. It has been non-natively established in Mexico as well, though it is not considered invasive by the Global Register of Introduced and Invasive Species (GRIIS).

Diet and behavior

The pinktail chalceus is a fast-moving and active fish that stays near the river's surface. It tends to cluster together in schools. Its diet generally consists of small invertebrates; when searching for food, it may leap out of the water to target a bug above the surface. It is notably skittish. This is a trait it shares with the yellowfin chalceus.

In aquaria

The pinktail chalceus is moderately popular in the aquarium trade, though it requires a larger aquarium than many prospective keepers have access to (55 gallons or above). It has enough of a reputation for jumping out of its tank (like its behavior in the wild) that sellers regularly warn buyers about it. This is more likely to happen if the pinktail is startled and does not have anyplace to take cover, such as plants or driftwood hideaways. Aquarists with adequate space to keep pinktails are advised to have a shoal larger than 6 to 8 specimens; anything lower, and squabbling is likely to happen. Because they are a fast and active species, the tank they live in doesn't need extraneous decor, but offering cover for them to hide in may make them more relaxed.

References

{{Taxonbar, from=Q3761027 Chalceidae Taxa named by Georges Cuvier Fish of South America Fish described in 1818