Buenos Aires tetra
Hardy silver freshwater fish with red fins and a black tail mark.
The Buenos Aires tetra is a resilient freshwater characin native to South America. It features silver scales, red-tipped fins, and a distinct black cross on its tail base. Popular in aquariums for beginners, it thrives in schools and accepts varied diets.
- Grows up to 7.5 cm with a lifespan of 6 years.
- Features a distinct black cross on the tail base.
- Native to the Río de la Plata Basin in South America.
- Requires schooling groups of five or more to reduce aggression.
What it is
This tropical fish displays a metallic silver body that reflects neon highlights under light. Its fins, including the pelvic, anal, and tail edges, show vivid red tips. A bold black cross shape marks the caudal peduncle, connecting the tail to the body. The dorsal fin often carries a red hint at its tip. Growing to 7.5 cm, it is larger than many tetra relatives. This hardy species suits novice hobbyists due to its durability and lack of complex care needs.
Where it lives
Native to South America, this species inhabits the Río de la Plata Basin. Populations spread across Argentina, Paraguay, Uruguay, and southeastern Brazil. Despite its name, it is not endemic to Buenos Aires Province. The type locality is Villarrica in central Paraguay. Wild specimens dwell in rivers, streams, ponds, and lakes. They require clean freshwater and struggle in salty or polluted conditions. A similar looking fish largely replaces it in the Buenos Aires region.
How it lives
These social fish swim in schools and thrive when kept with their own kind. Groups of five or more reduce individual aggression. They are omnivorous feeders, consuming worms, crustaceans, insects, and plant matter in the wild. In captivity, they accept live, frozen, and flake foods. Without adequate feeding, they may nip at long-finned tank mates or eat aquarium plants. Regular meals of bloodworms, Daphnia, and brine shrimp help maintain their health and colour.
Breeding and life cycle
Spawning occurs occasionally in home aquariums using slightly acidic water. Adults scatter eggs into the environment, leaving fertilization to chance. A separate breeding tank helps protect the offspring. Parents should be removed after laying eggs, as they often consume the young. Fry hatch within 24 hours. For the first three or four days, the young survive by eating their egg sacs before becoming free swimming.
Fish and people
Aquarists value this tetra for its resilience and striking appearance. It is considered optimal for beginners due to its low maintenance requirements. Keepers must provide a maintained freshwater tank and regular feeding. Overfeeding should be avoided by offering only what the fish consume in three minutes. While not a food fish, it plays a role in the ornamental trade. Its active schooling behaviour adds movement to community tanks.
Questions people ask about Buenos Aires tetra
What do Buenos Aires tetras eat?
They are omnivores that eat worms, crustaceans, insects, and plants. In aquariums, they accept high quality flake food, live bloodworms, Daphnia, and brine shrimp. Vegetables should also be included in their diet for optimal health.
Are Buenos Aires tetras aggressive?
They can nip at long-finned tank mates if not well fed. Keeping them in schools of five or more significantly decreases this aggression. They are generally hardy community fish when their social needs are met.
Where are Buenos Aires tetras found in the wild?
They originate from South America, specifically the Río de la Plata Basin. Their range includes Argentina, Paraguay, Uruguay, and southeastern Brazil. They live in freshwater rivers, ponds, lakes, and streams.
Good reading and sources
- Buenos Aires tetra on WikipediaEncyclopedia
- More photos on Wikimedia CommonsPhotos
- Wikidata recordOpen data
The facts on this page come from the Wikipedia article "Buenos Aires tetra", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.
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