The Beginner’s Guide to Buenos Aires Tetra Care

The Buenos Aires tetra or red cross tetra, scientifically known as Hyphessobrycon anisitsi, is a popular freshwater fish species in the aquarium trade. Buenos Aires tetra is not a picky one at all, it lives long and is easy to breed. The fish is quite hardiest and adapts well to most of tank water parameters and so it doesn’t require any special keeping conditions. This is a perfect fish for beginner aquarists. However, it has some peculiarities in terms of keeping you have to know to keep the fish successfully. This and many other information you will find in our article.

Habitat in the wild

Buenos Aires tetra was described by an ichthyologist Carl Henry Eigenmann in 1907. Buenos Aires tetra dwells in South America in Argentina, Brazil, and Paraguay. Hyphessobrycon anisitsi is primarily found in slow-moving rivers, streams, and flooded areas of the Paraná River basin in South America.

This is a schooling fish, that lives in large amount of biotopes including: rivers, streams, lakes and ponds. These tetras prefer slow to moderate water flow. They are not typically found in fast-moving or turbulent waters. In their natural habitat, Hyphessobrycon anisitsi inhabits areas with dense vegetation. They are commonly found in areas with submerged aquatic plants, floating plants, and marginal vegetation along the riverbanks.



The Buenos Aires tetra has a distinct and eye-catching appearance. The body of a Buenos Aires tetra is relatively elongated and laterally compressed, typical of many tetra species. It has a streamlined shape, allowing for agile movement in the water.

The body coloring is silvery, the back is brown and olive, dorsal, anal and abdominal fins are reddish or yellowish. The upper side of the fish iris is red. There is a dark diamond shaped spot near the tale fin base. The distinctive coloration and prominent black spot make the Buenos Aires tetra an attractive addition to freshwater aquariums. Their vibrant fins and active swimming behavior further enhance their visual appeal.

The Albino Buenos Aires Tetra is a color morph of the Buenos Aires Tetra (Hyphessobrycon anisitsi) that exhibits a lack of pigmentation, resulting in a pale or white appearance. They have a pale or white body coloration instead of the typical silver or gray color seen in their wild-type counterparts.


How big do buenos aires tetras get?

If compared with other tetra species it is quite a large fish. Its body length can be up to 2.5-3 inches (6-8 cm) in length. This is the average size for adult specimens of this species. However, that individual growth rates and sizes can vary slightly depending on factors such as genetics, diet, and environmental conditions.


How long do buenos aires tetras live?

Buenos Aires tetras have an average lifespan of around 5 to 7 years when kept in proper aquarium conditions. However, it’s important to note that individual lifespans can vary. Factors such as genetics, water quality, diet, and overall care can influence the longevity of the fish. Providing a suitable environment, including proper water parameters, a balanced diet, and a stress-free habitat, can help maximize the lifespan of Buenos Aires tetras in captivity.

Common NameBuenos Aires Tetra; red cross tetra; red cross fish
Scientific NameHyphessobrycon anisitsi
OriginParaná River basin in South America (Argentina, Brazil, Paraguay)
SizeUp to 2.5-3 inches (6-8 cm)
AppearanceSilvery body with a black spot at the base of the tail fin
Fin ColorsRed or orange
TemperamentGenerally peaceful, but can be slightly nippy in smaller groups
Preferred Water Temp.68-79°F (20-26°C)
Preferred pH Level6.5-7.5
DietOmnivorous; accepts high-quality flakes, pellets, live, and frozen foods
CompatibilityGenerally compatible with non-aggressive fish species
Group BehaviorShoaling fish; keep in groups of at least six individuals
Aquarium SetupHeavily planted with hiding spots and open swimming areas

Difficulties in keeping

The Buenos Aires tetra is good for beginner aquarists, since it is rather simple in care, enduring and doesn’t need any special tank conditions. But…

Buenos Aires tetra nips other fishes fins as well as it may crop soft and delicate tank plants. So you should be careful when keeping it planted tanks. The tank should be closed with a lid, because the fish can jump out of the water.

You should keep them in a school not less than 7 species; if there are less of them, they will demonstrate aggression towards their tank mates. Besides this red cross tetra is very timid and if it feels danger, the whole school hides among thick tank plants. The fish may also show aggression towards its kind.

Care and keeping in a tank

Since the fish is undemanding, keeping Buenos Aires tetra even in a community tank isn’t a difficult or troublesome thing to do. However, you should keep in mind that the fish may be aggressive and it’s better to provide it with fast and equally sized tank mates. The tank has to be tightly closed since the fish may jump out of it.

Keep in mind that the Buenos Aires tetra eats almost all kinds of tank plants except maybe java moss and anubias. If presence of greenery in a tank is crucial for you, tetra is definitely not your type of fish. You can reduce their craving for eating tank plants by adding food with high vegetable content into the diet.

Tank size

A minimum tank size of 20 gallons (75 liters) is recommended for a small school of Buenos Aires tetras. This provides enough swimming space and allows for proper filtration and maintenance. Buenos Aires tetras are active swimmers and appreciate open swimming areas. It’s important to provide them with ample space to move around and exhibit their natural behaviors. Balancing the tank with suitable plants, decorations, and open areas will create a more natural and comfortable environment.

Water parameters

In general, the Buenos Aires tetra is completely not picky.

Hyphessobrycon anisitsi is a tropical fish species that thrives in relatively warm water temperatures. The recommended temperature range for Buenos Aires tetras is typically between 68-79°F (20-26°C). This temperature range provides the ideal conditions for their overall health, activity, and breeding. Buenos Aires tetras can tolerate minor temperature variations for short periods. However, sudden or extreme temperature changes can be detrimental to their health.

The ideal pH range for Buenos Aires tetras is around 6.5-7.5. This range provides a moderately acidic to neutral environment, which mimics their natural habitat in the Paraná River basin.

General Hardness (GH): Buenos Aires tetras can tolerate a moderate range of GH levels. Ideally, the GH should be maintained within the range of 4-12 dGH (degrees of General Hardness). This range provides them with the necessary minerals and ions for their overall health and well-being.


There are no special requirements to the bottom substrate or to the tank lighting.

Ultimately, the choice of substrate depends on your preferences, the desired aesthetics, and the compatibility with your aquarium’s setup. Whichever substrate you choose, it’s essential to properly clean and rinse it before adding it to the aquarium to remove any debris or dust. Additionally, regular maintenance, such as vacuuming the substrate during water changes, is important to prevent the buildup of waste and maintain water quality.


In the wild it feeds on insects and algae. The Buenos Aires tetra isn’t demanding in terms of food – it eats frozen, live and artificial food.

A staple part of their diet can consist of high-quality flake or pellet foods specifically formulated for tropical fish. Look for products that contain a variety of ingredients such as fish meal, shrimp, spirulina, and plant matter.

This tetra crops fresh shoots of tank plants. Therefore, including vegetable food into the diet is a must. Some tetras also nibble on algae, so allowing a bit of algae growth in the tank can provide them with natural grazing opportunities.

Though it prefers live food, especially daphnia; it catches bloodworm while it is falling to the tank bottom. It doesn’t like eating food from the bottom and that’s why it’s better to feed it with slowly drowning food types, that it will gradually eat.

Tank mates

Buenos Aires tetras are shoaling fish and thrive when kept in groups of six or more individuals. They feel more secure and display their natural behaviors when kept in a sizable group. Buenos Aires tetra swim in schools and they are active all the time. At the slightest sign of danger the whole school hides in tank plants. Keeping the fish in a school of its kind is what reduces its natural aggressiveness.

Buenos Aires tetras (Hyphessobrycon anisitsi) are generally peaceful fish that can coexist with a variety of tank mates. However, slow and long finned fishes (goldfishes, angelfishes, guppies) will anyway suffer when dwelling in one tank with Buenos Aires tetra.

Here’s a table suggesting potential tank mates for Buenos Aires tetras (Hyphessobrycon anisitsi) in a community aquarium:

Neon Tetra (Paracheirodon innesi)Peaceful1-1.5 inches (2.5-3.8 cm)
Ember Tetra (Hyphessobrycon amandae)Peaceful0.8-1 inch (2-2.5 cm)
Harlequin Rasbora (Trigonostigma heteromorpha)Peaceful1-1.5 inches (2.5-3.8 cm)
Cardinal Tetra (Paracheirodon axelrodi)Peaceful1.5 inches (3.8 cm)
Cherry Barb (Puntius titteya)Peaceful2 inches (5 cm)
Panda Corydoras (Corydoras panda)Peaceful1.5 inches (3.8 cm)
Honey Gourami (Trichogaster chuna)Peaceful2 inches (5 cm)
Dwarf Gourami (Trichogaster lalius)Peaceful2-3 inches (5-7.6 cm)
Swordtail (Xiphophorus hellerii)Peaceful3-4 inches (7.6-10 cm)
Black Skirt Tetra (Gymnocorymbus ternetzi)Semi-Aggressive2.5 inches (6.4 cm)
Pearl Gourami (Trichogaster leeri)Peaceful4-5 inches (10-12.7 cm)
Zebra Danio (Danio rerio)Active, Peaceful2 inches (5 cm)
Bristlenose Pleco (Ancistrus sp.)Peaceful4-6 inches (10-15 cm)

Gender differences: male vs female

Determining the sex of Buenos Aires tetras can be challenging, especially in younger or less mature individuals. It’s often easier to differentiate the sexes during breeding periods or when females are visibly carrying eggs. If you are specifically interested in breeding Buenos Aires tetras, a more accurate method of sex determination would involve observing their courtship behavior and the development of secondary sexual characteristics, such as the formation of breeding tubercles on the males’ gill covers or pectoral fins.

There are some subtle differences between male and female Buenos Aires tetras that can help distinguish between the two genders. Here are some characteristics to look for:

  1. Body Shape: Male tend to be slimmer and more streamlined compared to females, which can have a slightly rounder belly, particularly when carrying eggs.
  2. Coloration: In terms of color, males often exhibit more intense and vibrant hues compared to females. Their fins, especially the dorsal fin, tend to be more brightly colored.
  3. Black Spot: Both male and female Buenos Aires tetras have a prominent black spot near the base of the tail fin, known as the caudal peduncle. However, the intensity and size of the spot can vary among individuals, and it may be more pronounced in males.
  4. Behavior: During breeding and courtship, males may display more active and aggressive behavior, such as chasing and displaying their vibrant colors to attract females.


Prepare a small tank (up to 20 liters capacity) with fresh settled water for breeding. It’s good if the tank is elongated, 25-30 cm high. Leave its center empty and put some tank plants near the walls.

When everything is ready, put a female and two male there. The Buenos Aires tetra should live separately for several days before this. At first the female wards off the males and they stay on the other side of the tank.

This can last for a day and sometimes longer, till reproductive products get ready. Then, usually in the morning, the males start haunting the female fish and they bring her into the center of tank plants, where she lays eggs and they are fertilized.

The eggs are very small and they are scattered in large numbers in many different directions; they stick to tank plants and spill on the tank bottom. This game is repeated several times. Each time the Buenos Aires tetra female lays eggs she and the males eat the eggs, but there are so many of them, that still about several hundreds of eggs are left.

After the Buenos Aires tetra spawns several times, you should remove both of them from the tank and put them into different volumes, so the female can rest.

In 2-3 days small juveniles hatch from the eggs and they hang of tank plants and walls. During this time you should feed them with infusorian or live small microorganisms and sufficiently aerate the tank water.

On the second day of their life the juveniles start swimming in schools and stay where there is a lot of food and eat it. They grow very fast and on the 8-10th day of their life they eagerly feed on cyclops. Next year the juveniles become reproductive.

In 10-15 day you can repeat the spawning with the same female, but it’s better to put some other male. During the second spawning there are usually less eggs.