The Buenos Aires Tetra, Hemigrammus anisitsi or Hemigrammus caudovittatus (junior synonym) comes from South America. It occurs in the Buenos Aires region of Argentina including the Rio de la Plata. The Buenos Aires Tetra also is reported to be in Brazil and Paraguay, including in the Rio Parana and the Rio Uruguay.
Buenos Aires is on latitude 34̊ 35' South. This is about the same distance from the Equator as Adelaide in South Australia, Los Angeles in California, Charlotte in North Carolina, Algiers in Algeria and Auckland in New Zealand. The Buenos Aires Tetra is able to take lower temperatures than the tetras which come from the tropics.
The Buenos Aires Tetra is much more flexible than most tetras. It can take temperatures from about 15̊ C (60̊F) to 30̊ C (86̊ F), pH from 5.5-8.5, and either soft or hard water. Although generally kept as a tropical fish, it will survive in unheated aquariums as long as the room temperature does not get very low. Acclimatization to an unheated tank in the winter has to be done very slowly (Over several weeks), but in warmer weather there is no problem. For a mixed tank of tropical fish including Buenos Aires Tetras I suggest a temperature of 24̊ C (75̊ F), and a neutral pH.
The Buenos Aires Tetra will eat any normal fish food. They are plant eaters and if live plants are put in expect them to get eaten. Some plant food can be provided for them. I use Duckweed as an easily grown plant food source. Like most fish Buenos Aires Tetras like live food like mosquito larvae, daphnia etc. They also like frozen Blood Worms. This fish seems to require more food than most fish of the same size. It is necessary to be careful to avoid polluting the aquarium by putting too much food in.
The Buenos Aires Tetra is a schooling fish and a school of six or more is less likely to do nasty things to the other fish. This is a more aggressive fish than most tetras, so although it fits well with the more robust tetras, barbs, Gouramis, Danios, etc. I do not recommend it as a companion for the smaller tetras like the Neon Tetras, small Cardinal Tetras, or fish with long fins like Siamese Fighting Fish, Guppies, or Endlers Guppies.
Suitable companions include Rummy Nose Tetras, Harlequin Rasboras, Lemon Tetras, Black Widow Tetras, Emperor Tetras, Head and Tail Light Tetras, Glass Bloodfin Tetras, Zebra Danios, and larger White Cloud Mountain Minnows and well as the Corydoras Catfish like Peppered Catfish.
The Buenos Aires Tetra is an easy fish to breed. It produces a lot of eggs, but is an egg eater so is normally removed after spawning. The fry grow quickly and soon start getting the toughness of their parents.
Sources and Picture Credits
For general information, I am indebted to the following sources: Zookoll, peces del Rio de la Plata ,www.petportal.com,The Tropical Tank, Aquatic Hobbyist, Fishlore.com, Pet Education.com, Fish Base, Aquatic community, Mongabay.com,