''Tyttocharax madeirae'', the blackedge tetra, also known as the bristly-mouthed tetra or the blue tetra, is a small freshwater fish of the family

Characidae Characidae, the characids or characins is a family of freshwater subtropical and tropical fish, belonging to the order Characiformes. The name "characins" is the historical one, but scientists today tend to prefer "characids" to reflect their st ...

found in the

Amazon basin The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries of Bolivi ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

. It was first caught by Edgar A. Smith in 1912 in

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

and described by

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish ( Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 33,400 species of fish had been described as of Octobe ...

Henry Weed Fowler Henry Weed Fowler (March 23, 1878 – June 21, 1965) was an American zoologist born in Holmesburg, Pennsylvania. He studied at Stanford University under David Starr Jordan. He joined the Academy of Natural Sciences in Philadelphia and worked as ...

in 1913. Unlike many other charcharins, ''T. madeirae'' has seen little inclusion into the aquarium trade.

Discovery and naming

Along with other descriptions made by Fowler in 1913, eight specimens of ''T. madeirae'', including the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

and the

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). Of ...

, were collected by Edgar A. Smith during a 1912-1913 expedition to the Amazon basin in Brazil along the

Madeira River The Madeira River ( pt, Rio Madeira, link=no ) is a major waterway in South America. It is estimated to be in length, while the Madeira-Mamoré is estimated near or in length depending on the measuring party and their methods. The Madeira is ...

. In his description, Fowler named the species for the Madeira River.

Distribution

''Tyttocharax madeirae'' has been found in the lower and middle

tributaries A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainage b ...

of the Amazon basin, being found in the nations of Brazil,

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

, and

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

. It is pelagic, and according to observations by

Herbert R. Axelrod Herbert Richard Axelrod (June 7, 1927 – May 15, 2017) was an American tropical fish expert, a publisher of pet books, and an entrepreneur. In 2005 he was sentenced in U.S. court to 18 months in prison for tax fraud. Early life Axelrod was born ...

were found in shallow waters 0.3 to 0.6 meters deep (1 to 2 feet) at most. In a sampling expedition by Barros et al., ''T. madeirae'' accounted for 0.82% of the total 5508 collected specimens and occurred in 13.6% of the sampled streams of the Madeira-Purus interfluvial plain.

Description

Fowler did not describe the colors of a living ''T. madeirae'', however, it was described as palish brown when in alcohol, exhibiting

countershading Countershading, or Thayer's law, is a method of camouflage in which an animal's coloration is darker on the top or upper side and lighter on the underside of the body. This pattern is found in many species of mammals, reptiles, birds, fish, and ...

with a paler underside. ''T. madeirae'' is considered small, with the average length of the species being 1.5 cm (0.59 inches) and ranging from 1.1 to 1.8 cm (0.43 to 0.71 inches).

Ecology

''Tyttocharax madeirae'' is an

invertivore Feeding is the process by which organisms, typically animals, obtain food. Terminology often uses either the suffixes -vore, -vory, or -vorous from Latin ''vorare'', meaning "to devour", or -phage, -phagy, or -phagous from Greek φαγε ...

, specializing on aquatic invertebrates while also occasionally preying on terrestrial vertebrates which may fall into the water.

References

{{Taxonbar, from=Q5694628 Xenurobryconini Tetras Taxa named by Henry Weed Fowler Fish described in 1913