''Stygichthys typhlops'', the blind tetra or Brazilian blind characid, is a species of

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

in 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 ...

and the only member of the genus ''Stygichthys''. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to caves in northern

Minas Gerais Minas Gerais () is a state in Southeastern Brazil. It ranks as the second most populous, the third by gross domestic product (GDP), and the fourth largest by area in the country. The state's capital and largest city, Belo Horizonte (literally ...

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 ...

. Like other cave-adapted fish (e.g. the cave form of the

Mexican tetra The Mexican tetra (''Astyanax mexicanus''), also known as the blind cave fish, blind cave characin, and blind cave tetra, is a freshwater fish of the family Characidae of the order Characiformes. The type species of its genus, it is native to th ...

), the Brazilian blind characid is blind and lacks pigmentation. It reaches up to about in

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

. It is solitary and when kept together in an aquarium, individuals are indifferent to each other. Initially only known from a specimen collected in 1962, it was rediscovered in 2004 by researchers led by the

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 ...

Dr Cristiano Moreira from the

University of São Paulo The University of São Paulo ( pt, Universidade de São Paulo, USP) is a public university in the Brazilian state of São Paulo. It is the largest Brazilian public university and the country's most prestigious educational institution, the best ...

. According to locals it was relatively common in the Jaíba region until the early 1990s, but generally not seen afterwards as extensive water extraction had significantly lowered the

water table The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water. It can also be simply explained as the depth below which the ground is saturated. T ...

, resulting in many wells and springs drying out. This represents a serious threat to the continued survival of ''Stygichthys typhlops''. It is recognized as an

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...

species by Brazil's Ministry of the Environment. Although there are many cave-adapted

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...

species in mainland South America, there are only two known cavefish species from other orders: ''Stygichthys typhlops'' and the knifefish ''

Eigenmannia vicentespelaea ''Eigenmannia vicentespelaea'' is a species of weakly electric knifefish in the family Sternopygidae. Native to the São Domingos karst area in central Brazil, it is the only known knifefish to exclusively inhabit caves. Measuring up to lo ...

''.

References

Cave fish Blind animals Characidae Monotypic fish genera Fish of South America Fish of Brazil Endemic fauna of Brazil Taxa named by Martin Ralph Brittan Taxa named by James Erwin Böhlke Taxonomy articles created by Polbot {{Characiformes-stub