Mexican tetra
Channel: all the knowledge of the universe PRINCIPIA
Date: 2021-12-05

Mexican tetra, by Wikipedia https://en.wikipedia.org/wiki?curid=3209 / CC BY SA 3.0

#IUCN_Red_List_least_concern_species
#Tetras
#Astyanax_(fish)
#Freshwater_fish_of_Mexico
#Freshwater_fish_of_the_United_States
#Cave_fish
#Blind_animals
#Least_concern_biota_of_the_United_States
#Fish_described_in_1853
#Taxa_named_by_Filippo_De_Filippi
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 the Nearctic realm, originating in the lower Rio Grande and the Neueces and Pecos Rivers in Texas, as well as the central and eastern parts of Mexico.
Growing to a maximum total length of 12 cm （4.7 in）, the Mexican tetra is of typical characin shape, with unremarkable, drab coloration.
Its blind cave form, however, is notable for having no eyes or pigment; it has a pinkish-white color to its body （resembling an albino）.
This fish, especially the blind variant, is reasonably popular among aquarists.
A. mexicanus is a peaceful species that spends most of its time in midlevel water above the rocky and sandy bottoms of pools and backwaters of creeks and rivers of its native environment.
Coming from a subtropical climate, it prefers water with 6.
5–8 pH, a hardness of up to 30 dGH, and a temperature range of 20 to 25 °C （68 to 77 °F）.
In the winter, some populations migrate to warmer waters.
Its natural diet consists of crustaceans, insects, and annelids, although in captivity it is omnivorous.
The Mexican tetra has been treated as a subspecies of A. fasciatus, but this is not widely accepted.
Additionally, the blind cave form is sometimes recognized as a separate species, A. jordani, but this directly contradicts phylogenetic evidence.
Mexican tetra in blind cave fish form A. mexicanus is famous for its blind cave form, which is known by such names as blind cave tetra,
blind tetra （leading to easy confu...