''Pristella maxillaris'' is a species of

characin Characiformes is an order of ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, more than 2000 different species are described, including the well-known piranha and tetras.; Buckup P.A.: "Relationsh ...

in the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

'' Pristella'', and is commonly known as the X-ray fish or X-ray tetra because of its translucent body.

Description

It is a widely distributed and adaptable fish, found in the

Amazon Amazon most often refers to: * Amazon River, in South America * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon (company), an American multinational technology company * Amazons, a tribe of female warriors in Greek myth ...

and

Orinoco The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers approximately 1 million km2, with 65% of it in Venezuela and 35% in Colombia. It is the List of rivers by discharge, f ...

basins, as well as coastal rivers in

the Guianas The Guianas, also spelled Guyanas or Guayanas, are a geographical region in north-eastern South America. Strictly, the term refers to the three Guianas: Guyana, Suriname, and French Guiana, formerly British, Dutch, and French Guiana respectiv ...

in both

acidic An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen cation, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid. The first category of acids are the ...

and

alkaline In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The ...

waters. Unlike most other

characins Characidae, the characids, is a family of freshwater subtropical and tropical fish belonging to the order Characiformes. They are found throughout much of Central and South America, including such major waterways as the Amazon and Orinoco Rivers ...

, it is tolerant of (and sometimes found in) slightly

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

water. It is small (up to around in length) and lives in large groups, and males can be distinguished from females by being smaller and thinner than the females. Like most other

tetra Tetra is the common name of many small freshwater characiform fishes. Tetras come from Africa, Central America, and South America, belonging to the biological families Characidae, Alestidae (the "African tetras"), Lepidarchidae, Lebiasi ...

s, it feeds primarily on small insects and planktonic animals.

Nomenclature

Older aquarium books often refer to this species by the

junior synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...

''Pristella riddlei''. Aquarists tend to refer to this fish as the golden pristella tetra, though some call it the X-ray tetra, instead. Other common names include goldfinch tetra, a reference to the similarly coloured goldfinch, and pristella tetra, a modification of its Latin name. A common name that was once widespread but is now rarely used is signal tetra, a reference to the similarity between the yellow and black dorsal fin and the arm of a semaphore railway signal.

In aquaria

''Pristella maxillaris'' is a small, adaptable fish that is often kept in a home aquarium and will eat most

fish food Aquarium fish feed is plant or animal material intended for consumption by pet fish kept in aquariums or ponds. Fish foods normally contain macronutrients, trace elements and vitamins necessary to keep captive fish in good health. Approximately ...

s. It is tolerant of a range of water chemistry values ( pH 6–8; hardness up to 20 dGH). As a

shoaling In biology, any group of fish that stay together for social reasons are shoaling, and if the group is swimming in the same direction in a coordinated manner, they are schooling. In common usage, the terms are sometimes used rather loosely. Ab ...

species, it is usually kept in groups of at least six specimens and away from aggressive or

predatory Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

tankmates, but is otherwise easily kept in the community tank. The minimum aquarium size is typically 60 x 30 cm (15 Gallons). Ideally, this species can be kept in a tank containing live plants that provide cover and comfort to the tetras, they thrive in a planted environment with well filtered and oxygen rich water with plenty of open swimming space and a greater swimming area. Some retailers offer an albino variant, which are nearly transparent with visible organs, while keeping their characteristic red tail. This variant is named the "Red Belly X Ray" tetra. Their care specifics are exactly the same as traditional ''Pristella maxillaris''.

References

External links

*
Pristella Tetra Fact Sheet
{{Taxonbar, from=Q540539 Pristellini Fish described in 1894 Taxa named by Albert B. Ulrey Tetras of Brazil Fish of Guyana Fish of French Guiana