Buenos Aires Tetra: Care Guide for a Harmonious Tank

Charlie Morton

Charlie Morton


Buenos Aires Tetra

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Buenos Aires tetra have long been popular aquarium fish for both tropical aquariums and cold water setups.

However, some aquarists are surprised to learn that Buenos Aires tetras grow to a larger size than most other tetras and can become aggressive towards their tank mates, even destroying aquarium plants in some circumstances.

In this care guide, I’ll be sharing the best ways to create a harmonious setup for these misunderstood fish, where they can live peacefully and happily in their carefully crafted surroundings.

Buenos Aires Tetra Care at a Glance

Buenos Aires Tetra Info
Scientific NamePsalidodon anisitsi / Hyphessobrycon anisitsi
OriginSouth America: Argentina, Southeastern Brazil, Paraguay
TemperamentPeaceful to semi-aggressive fish
Lifespan5 years
Minimum Tank Size30 gallon
BreedingEgg scatterer
pH5.5 – 7.5
HardnessUp to 18 dGH
Temperature64 to 82 F (18 to 28 C)

Species Overview

Origin and Background

The Buenos Aires tetra is a South American species of fish belonging to the tetra family.

As their name suggests, one of their home countries is Argentina, and these schooling fish come from cooler, more temperate regions than many of their Amazonian cousins.

This prolific, robust species have long been popular in the aquarium trade as they can survive in an unheated aquarium in a warm room, as well as in tropical tanks.

In the wild, Buenos Aires tetras occupy rivers, lakes, ponds, and streams, as well as seasonal flood plains.

Size and Appearance

Buenos Aires tetra are one of the larger tetras and can occasionally exceed 3 inches in length.

2.5 inches is a more typical size, however, and females are slightly bigger than males.

Buenos Aires tetra are pretty silver fish with red fins and an iridescent shine. Their red fins and sparkling iridescence become especially pronounced at breeding time, particularly in males.

Color Variations

Some alternative color variants of Buenos Aires tetra have been selectively bred for the aquarium market.

It’s possible to find an albino form with a white body, red fins, and red eyes, although they tend to be less robust than the regular species.

Some forms of Buenos Aires tetra in pet stores also have yellowish patches at the base of the tail.

Buenos Aires Tetra Care Guide

Tank Size

Buenos Aires tetra are schooling fish that need to be kept in groups of 6-8 or more, with ample room to swim around in.

Because they’re one of the largest and most active tetras, they should never be kept in fish tanks shorter than 36 inches long.

This is the standard length for 30-gallon aquariums, but it must be stressed that these fish need a long tank with plenty of horizontal swimming space rather than a tall aquarium.

Tank Environment

As already discussed, Buenos Aires tetra are active fish that need plenty of open water swimming space.

For this reason, the tank shouldn’t be planted too densely. Even if you try introducing them to a densely planted tank, they might soon create more swimming space because Buenos Aires tetra have a reputation for eating live plants!

But while many aquarists have had trouble with Buenos Aires tetra eating their aquatic plants, others have reported no problems. This might be down to their feeding regime, which we’ll discuss in a moment!

In general, a few tough plants like anubias, Java fern, and vallisneria are less likely to be eaten, provide some useful cover for fish that wish to hide, and the tank more dynamic and beautiful. Plastic plants are another option.

Buenos Aires tetra will rarely visit the lower reaches of the tank, but you could create some rocky caves for their tank mates to hide in.


Driftwood often looks stunning with schooling fish, and hardwood driftwood can also release amber-colored, acidic tannins into the water, which some aquarists believe supports the health of softwater fish.

Water Temperature

Buenos Aires Tetra are unusual tetras in that they can tolerate relatively cold water as well as warm water. This is great news if you’re interested in keeping other coldwater fish species.

But by ‘cold water’, I don’t imply that Buenos Aires Tetra can be kept in freezing temperatures! Their preferred temperature range is between 65-78°F, meaning you’ll still need to site their tank in a consistently warm room to avoid them catching a chill.

Water Parameters

The waters that Buenos Aires tetra normally inhabit in the wild are soft and acidic. It’s better, therefore, if you can replicate these conditions at home.

Get yourself a reliable aquarium test kit, and check that your pH is between 5.5 to 7.5. Water hardness should remain below 18 dGH.

Because they’re hardy fish, Buenos Aires tetra will probably accept water conditions slightly outside this range, but it’s less than ideal.

As previously mentioned, you can make your water more acidic by adding materials that contain tannins such as untreated driftwood, peat, and Indian almond leaves.

Buenos Aires tetra are freshwater fish and won’t tolerate salty or brackish water.


As with any type of fish, Buenos Aires tetra require an efficient aquarium filter to maintain high water quality for them to remain happy and healthy. Relative to other tetras, Buenos Aires tetras like particularly clean, well-oxygenated water.

In general, Hang-on-back filters and internal power filters are good options for small to medium-sized tanks, and canister filters are the best for tanks over 55 gallons.

Because they’re strong swimmers, Buenos Aires tetra can handle a strong filter flow, and may even enjoy swimming against it!


Buenos Aires Tetra have a voracious appetite and are quite unfussy in their eating habits! They’ll accept almost any type of commercial fish food, from tropical flake foods to small fish pellets.

But dried fish foods should always be supplemented with fresh and frozen foods such as bloodworms, tubifex worms, daphnia, brine shrimp, mosquito larvae, and vegetable supplements.

I’d normally only recommend feeding tetras twice a day, but if Buenos Aires tetras get too hungry, they’re more likely to begin nibbling at aquarium plants or even their tank mates!

A third feeding session in the middle of the day, therefore, may prove beneficial in alleviating aggressive behavior from your Buenos Aires tetra.

At the same time, be warned that overfeeding is one of the leading causes of water quality and health problems in aquarium fish. Never feed more than your fish can eat in 2 minutes.

Compatible Tank Mates

Buenos Aires Tetra

Buenos Aires tetra are larger, more boisterous fish than most of their tetra cousins, so shouldn’t be kept with small or fragile species like neon tetra or rummy nose tetra. They also have a reputation for nipping fins, so tank mates with long fins, like betta fish, guppies, and angelfish are best avoided.

Instead, keep your Buenos Aires tetra in a tank with other large or robust species that won’t be troubled by their feisty characters.

Other large tetras like black widow tetra and serpae tetra make good choices, as well as barbs, scissor tails, danios, gouramis, and rainbow fish.

Because they are extremely fast and agile, Buenos Aires tetra can also share a tank with semi-aggressive cichlids like convict cichlids, ram cichlids, and kribensis.

Bottom-dwelling fish like cory catfish, plecos, and Kuhli loaches also make excellent companions for Buenos Aires tetra since they generally inhabit a different part of the water column.

Coldwater Aquarium Tank Mates

The fish listed above are all suitable for heated fish tanks, but what about tank mates for Buenos Aires tetra in coldwater aquariums?

Zebra danios, rosy barbs, gold barbs, two spot barbs, and paradise fish are all good choices for tanks without a heater. Advanced aquarists could also consider the rainbow shiner (Notropsis chrosomus), and Pumpkin seeds (Lepomis gibbosus).

Because they’re such messy fish, goldfish are not a good match for Buenos Aires tetra, who need clean, well-oxygenated water to thrive.

Clean Up Crew Tank Mates

The bottom-dwelling fish mentioned above are great for eating up uneaten fish food and helping to keep the tank clean.

If you’re having algae problems, nerite snails are your best option since Buenos Aires tetra have been known to attack small shrimp such as cherry shrimp and ghost shrimp!

Reducing Aggression

To reduce the chances of your Buenos Aires tetra becoming aggressive, it’s important to keep them in a large enough group.

Because they’re schooling fish, Buenos Aires tetra need to be kept in groups of at least 6-8 to feel safe and relaxed. Any less than this and they’re more likely to fight with each other and nip the fins of long-finned fish.

As well as plenty of open swimming space, provide some tough live or synthetic plants to provide hiding places for potential targets of their aggression.

Some aquarists have also noted that they’re more likely to bother other fish when they’re hungry – see notes on feeding above!

Health and Disease

To remain happy and healthy, Buenos Aires tetra need good tank maintenance and high water quality.

If water quality deteriorates, these fish can become susceptible to the same diseases and health conditions that trouble other aquarium fish.

Ich, velvet, and flukes are all common parasitic diseases that can lie dormant in an aquarium for years until a weakened fish or poor water quality offers them a chance to take hold.

Similarly, bacterial and fungal infections like columnaris and water mold only tend to affect fish that are already in a vulnerable state.

As mentioned earlier, Buenos Aires tetra are prone to nipping each other’s fins when kept in small groups or when stressed. Nipped fins can lead to fin rot – a bacterial infection that can later invade the rest of the body.

Keeping Buenos Aires tetra in groups of 8 or more, in clean water with plenty of open swimming space is, therefore, the best defense against stress and unnecessary diseases.


Buenos Aires tetra are easier to breed than many of their tetra cousins. Even aquarists with moderate experience in breeding easier fish like livebearers can have a go at rearing them!

You can either breed them in pairs or groups of equal numbers of male and female fish in a specially designated breeding tank.

How To Breed Buenos Aires Tetra

  • First, move the fish you’d like to breed from to your breeding tank. The ideal setup would be a 20 or 30-gallon tank with a sponge filter and some robust plants or spawning mop to scatter their eggs onto.
  • Condition the parent fish by keeping them in soft water with a temperature of 75°F. Feed them on live foods like bloodworms and brine shrimp. If you can’t access live foods, then frozen foods are your next best bet.
  • When your Buenos Aires tetra are getting ready to spawn, the male fish will display especially bright red fins and the females will develop large bellies, full of eggs. You may also notice the males chasing the females around persistently!
  • Spawning often takes place at dawn. Adhesive eggs are dispersed over the live plants or spawning mops. The parents may then eat the eggs, so they need to be removed directly after spawning is completed.
  • Buenos Aires tetra fry hatch in just 24 hours. After 3-4 days, they will have consumed their egg sacs and be free swimming. Begin by feeding them on fry infusoria, and later on baby brine shrimp, micro worms, and ground-up flake food.


When they’re kept in good condition, Buenos Aires tetra can live to over 5 years of age. There are even reports of really healthy individuals reaching 8 years in captivity, which is impressive for a tetra.

For them to reach their maximum lifespan, their diet, water quality, and quality of care must be of the highest order.

Tank Maintenance

Some top tips for keeping your Buenos Aires Tetra in tip-top condition!

Buying Guide

As a popular fish, Buenos Aires tetra are available from many pet stores and online aquarium retailers.

When buying in a pet store, always choose fish that are healthy-looking, with shiny scales, bright eyes, and colorful fins. When buying online, check reviews first to make sure you’re buying from a reputable dealer.

Prices for Buenos Aires tetra range from $3-10 per fish in 2023.

Final Thoughts

Buenos Aires tetra are a pretty and robust type of tetra that can be kept in tropical aquariums as well as coldwater setups.

Just remember that these large fish are more active and boisterous than many of their cousins, so should always be kept in groups of 6 or more with plenty of swimming space.

To be on the safe side, never keep them in a tank with small or vulnerable fish or delicate plants.

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