Buenos Aires Tetra Fish Species Profile

Characteristics, Origin, and Helpful Information for the Hobbyist

Buenos Aires Tetra
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The Buenos Aires tetra is extremely popular due to its hardiness and ease of care. These fish were once sold in large numbers, but due to their propensity for eating aquarium plants, they have become less popular over the years. Specimens are mostly captive-bred from commercial fish farms in Florida.

Species Overview

Common Names: Buenos Aires tetra, diamond spot characin, red cross fish

Scientific Name: Hyphessobrycon anisitsi

Adult Size: 2.75 inches (7 centimeters)

Life Expectancy: 5 years


Family Characidae
Origin Argentina, southeastern Brazil, Paraguay
Social Peaceful, shoaling fish
Tank Level Mid-level
Minimum Tank Size 30 gallon
Diet Omnivore
Breeding Egg scatterer
Care Easy
pH 5.8 to 8.5
Hardness Up to 35 dGH
Temperature 64 to 82 F (18 to 28 C)

Origin and Distribution

The Buenos Aires tetra derives its name from the capital city of Argentina. The city sits on the western shore of the Río de la Plata, located along the southeastern coastline of South America. Considered a river by some and a gulf by others, the Río de la Plata is formed by the joining of the Paraná and Uruguay Rivers, both of which are home to the Buenos Aires tetra. In the wild, they are additionally found in rivers, ponds, lakes, and streams. They are freshwater fish and do not do well in highly salty or polluted waters. 

Colors and Markings

The Buenos Aires tetra is one of the larger tetras as it can grow to nearly three inches in size. Its body is silvery with a narrow blue line that starts behind the gill and ends at the caudal (tail) fin, where there is a black diamond-shaped spot. The fins are orange-red and a splash of red can be seen at the top of the eye. Several color variations have been bred including one that has a yellow tail; there is also an albino variety.


Buenos Aires tetras are social fish that swim in schools. Although this species of tetra is generally peaceful, avoid keeping Buenos Aires tetras with smaller fish such as the neon tetra. Also, avoid housing them with long-finned fish such as the betta and angelfish. Buenos Aires tetras will nip at the fins of long-finned tankmates.

The Buenos Aires tetra does well with larger sized tetras, such as the black widow or serpae tetra, as well as with barbs, danios, gouramis, and rainbowfish. Bottom-dwelling fish are also good companions. A school of Buenos Aires tetras are also good dither fish among non-aggressive cichlids; they help relax cichlids enough to come out of hiding.

Buenos Aires Tetra Habitat and Care

The undemanding Buenos Aires tetra is adaptable to a range of aquarium conditions. Acceptable water temperatures can span all the way from the mid-60s to 80 degrees Fahrenheit, making it suitable for heated as well as unheated tanks. It is a highly active fish, and it does require a sizable open swimming space. Longer tanks are ideal.

The Buenos Aires tetra is not suitable for most live planted tanks, however, as it is known to devour vegetation. Use artificial plants instead, or select sturdy live plants such as anubias, Java fern, or vallisneria. Round out the décor with driftwood and rocks around the periphery of the tank, and your Buenos Aires tetras will be quite at home.

They are happy with any type of substrate and do fine with normal aquarium lighting. However, the tank should be securely covered as these fish are skilled jumpers and will probably do so if given the opportunity.

The Buenos Aires tetra is extra sensitive to the nitrates and phosphates that build up over time, and water hardness increases due to evaporation. To combat these ever-changing conditions, water should be replaced on a regular basis. At least 25 to 50 percent of the tank water should be replaced every other week especially if the tank is densely stocked.

Buenos Aires Tetra Diet and Feeding

Buenos Aires tetras are omnivores that will accept a wide variety of foods. Feed these tetras several times a day but feed only what they can consume in three minutes or less at each feeding.

In the wild, they primarily feed on worms, crustaceans, insects, and plants, but in the aquarium, they will generally eat all kinds of live, fresh, and flake foods. Given its propensity for eating live plants, provide this fish with some lettuce, spinach, or other vegetation to munch on. In lieu of fresh vegetation, you can provide a good quality spirulina flake food.

Flake, dried, and freeze-dried foods add well-needed variety to their diet and will be readily accepted. To keep these tetras at their best and most colorful, offer live foods such as bloodworms, daphnia, brine shrimp, and mosquito larvae. 

Gender Differences

Males of the species have brighter, redder fins and are generally more colorful overall, particularly during spawning. Females are larger and broader with a rounder belly. 

Breeding the Buenos Aires Tetra

Buenos Aires tetras are easy to breed; they are egg scattering fish that can be spawned in pairs or in groups. If spawned in a group, use approximately the same number of males as females. A mature female's belly will become nicely rounded when she is full of eggs. Choose males that are the most colorful.

Condition all spawning fish with live foods prior to spawning attempts. Keep the water slightly acidic to neutral with a pH of 6.5 to 7.2; keep the water temperature at 75 degrees Fahrenheit. Gentle filtration, such a sponge filter is recommended. Provide sturdy plants such as Java moss or spawning mops on which the fish will scatter their adhesive eggs.

This species will usually begin to spawn at dawn. Females may lay as many as 2,000 eggs, depositing them on the plants or green floss. Remove the adults once the eggs have been laid. After spawning, these fish exhibit no parental care and will eat the eggs and young, so make this your separate rearing tank.

The eggs will hatch in approximately 24 hours. In three to four days the fry will have consumed their egg sacs and will be free swimming. Initially, feed the fry infusoria or commercially prepared fry food such as Liquifry. As they grow larger, feed them freshly hatched brine shrimp, micro worms, or finely ground high-quality flake food or fry food.

More Pet Fish Species and Further Research

If Buenos Aires tetras appeal to you, and you are interested in some compatible fish for your aquarium, consider these species:

Check out additional fish species profiles for more information on other freshwater fish.