Buenos Aires Tetra: Species Overview

Category: Tetra

Common Names: Buenos Aires Tetra

Scientific Name: Hemigrammus caudovittatus

Family: Characidae

Minimum Tank Size: 10 Inches

Care Level: Easy

Temperament: Peaceful

Max Size: 2 ½ Inches

Temperature: 72-80 F

pH: 6.0-8.0

Tank Level: Bottom to Middle

Colors: Silver, Red

Diet: Omnivore

Breeding: Moderate

Buenos Aires Tetra Left Side

Buenos Aires Tetra: Species Overview

Buenos Aires tetras are colorful and active fish that are a joy to have in the tank. They’re popular because of their schooling ways, drawing people’s eyes when looking at your aquarium.

These are hardy fish and get along well with many species, so they’re a good fit for beginner fish keepers. Nevertheless, Buenos Aires tetras enjoy eating plants, so you’ll need to take care of live plants when setting up their tank.

Even though Buenos Aires tetras are easy to care for, it’s essential to provide them with the proper water conditions to keep them in optimal health. Read on to discover more about these unique and spunky fish.

Distinguishing Features

There are a few different types of Buenos Aires tetras, including:

  • Yellow tails
  • Alabino
  • Silver bodies

The silver body is the most common type of Buenos Aires tetra. These fish have an iridescent blue line that runs from the back of their gill to the end of their tail.

The point where the blue line meets the fin has a black-colored diamond spot.

Most Buenos Aires tetras also have reddish-orange fins and a similar color above their eye. The exception is their dorsal fin, which is almost always see-through.

Certain Buenos Aires tetras also have black and red markings on other parts of their bodies.

Nick Sc. [CC-BY-SA-3.0]


It likely comes as no surprise that the Buenos Aires tetra originates from Argentina. More specifically, they live in the La Plata region, where they enjoy the ponds, streams, and lakes this area has in addition to its main river.

However, you can also find Buenos Aires tetras outside of Argentina. For example, they’re common in neighboring Paraguay and the southeastern region of Brazil.

Buenos Aires tetras prefer clear freshwater in the wild. They enjoy areas with lots of plant vegetation, given that they’re a source of food and shelter.

These fish aren’t picky about the types of plants they have access to as long as they reach the mid-level of the water column, where they spend most of their time.

The substrate where Buenos Aires tetras live varies and impacts the fish little, given that they don’t frequent it. But a mixture of sand, mud from decaying organic matter, and stones are common.


Buenos Aires tetras are quite large for the tetra species, growing up to three inches long.

Females are often slightly larger than males, although the difference is more notable in the girth of the fish rather than their length.

If you want your Buenos Aires tetras to grow as large as possible, selecting a reputable breeder, offering them high-quality food, and providing a large tank are essential factors to improve the chances of that happening.


Buenos Aires tetras have a modest lifespan for the tetra family, averaging three to five years.

Genes play a role in your fish’s lifespan. But it’s equally essential to provide Buenos Aires tetras with the proper water conditions and a diverse array of food to help them maximize their potential lifespan.


It’s relatively easy to tell male and female Buenos Aires tetras apart as long as you have both genders in a tank.

The males typically have brighter colors than the females.

Additionally, female Buenos Aires tetras often grow slightly longer and have a wider appearance, particularly around their stomach, than males.


Buenos Aires tetras have a semi-peaceful temperament.

For starters, you must keep a minimum of six fish in a tank. That’s because these are schooling fish, so they’ll turn aggressive towards smaller fish out of frustration and anxiety if they don’t have enough of their species to socialize with.

Furthermore, even if you have at least six Buenos Aires tetras together, you’ll need to keep long-finned fish out of their tank, particularly if they have slow-moving tendencies.

Both males and females display similar peaceful and aggressive behaviors under the same conditions.

But overall, Buenos Aires tetras get along well with fish that are of a similar size or slightly bigger than them. These are active fish, so you can expect to see them play often.

Tank Parameters

If you’re ready to welcome Buenos Aires tetras into your home, you’ll need to prepare by setting up the following tank parameters.

Minimum Tank Size

It’s best to keep six Buenos Aires tetra fish in a 30-gallon tank at a minimum.

That means you’ll need to factor in five gallons of water for every additional fish of this species you want to add.

The reason it’s vital to give Buenos Aires so much space in their tank is because they’re active fish that love exploring. So, the larger the tank you can manage, the happier they’ll be.

Water Parameters

Below are the essential water parameters you’ll need to establish before introducing your Buenos Aires tetras to their tank.


Buenos Aires tetras have an exceptionally high tolerance for a range in water temperatures. They can live in water from 64°F to 82°F.

Ideally, you should try to give them water in the low to mid-70s as a happy medium.

Furthermore, even though these tetras can handle both cool and warm water, it’s vital to adjust them to any temperature changes gradually. Otherwise, it could shock their system.


Yet again, Buenos Aires tetras a hardy when it comes to pH levels. They can live in water with a pH between 5.8 (slightly acidic) and 8.5 (slightly alkaline).

We recommend trying to shoot for the middle, though, offering your tetras a pH around neutral (7.0).


Buenos Aires tetras are freshwater fish, so they won’t last long in saltwater conditions.

That said, you may have heard about freshwater aquarium salt. Such salt can help treat ill fish, as it helps boost their immune system.

But in most cases, you’re better off leaving salt out of a Buenos Aires tetra’s tank.

Tank Setup

Now that you know the water parameters to arrange for your Buenos Aires tetras, below are other factors to consider when setting up their tank.


Since Buenos Aires tetras live in the middle of their tank, you’re free to choose whatever substrate draws your attention.

The most common substrates fish keepers use are sand or fine gravel.

We encourage you to consider using a darker substrate, as that’s what Buenos Aires tetras encounter in the wild. It’ll also help them stand out more in the tank compared to a light-colored substrate.


Buenos Aires tetras enjoy having decorations for exploring and hiding. So, it’s wise to include at least one decoration that rises midway up the tank, giving them easy access to it.

Some excellent decorations to include in your Buenos Aires tank are:

  • Rocks
  • Caves
  • Driftwood

When arranging decorations in your aquarium, keep in mind that Buenos Aires tetras enjoy having open space to swim.

So, be sure to leave enough room in the middle of the tank for these fish to school.


It’s challenging to keep live plants in a Buenos Aires tetra tank, given that these fish love to eat them. Therefore, you’re often better off using artificial plants.

That said, some fish keepers report having decent luck with java fern. So it’s worth giving this plant a go if you have your heart set on providing your fish with a live plant.

Make sure the artificial plants are free of sharp edges that could cut your tetras.

Since these fish enjoy the protection of plants, placing them in thick groups around the perimeter of your tank is ideal.


Buenos Aires tetra fish require tank lighting on a medium setting. That way, the light will help them control their circadian rhythm, letting your fish know when it’s time for bed.

Of course, it’s easy to inadvertently mix up your fish’s sleep and waking habits if you often forget to turn their tank lamp on and off.

For this reason, purchasing a light with an automatic timer is best.


A filter is vital for Buenos Aires tetras. These filters control life-threatening toxins and help your tank stay clear.

However, a filter isn’t a replacement for water changes. You should aim to change approximately 25% to 50% of your Bueno Aires tetra’s water every one to two weeks.

Furthermore, check your filter regularly to clean it and ensure it’s functioning well.


Unlike many species of tropical fish, Buenos Aires tetras can live happily without a tank heater as long as your home remains between 64°F to 82°F.

Nevertheless, these tetras do well—and even thrive—with heaters, given that it helps the water remain at a consistent temperature.


Buenos Aires tetras survive on an omnivorous diet. They love live aquatic plants, but they also gobble up insects and crustaceans in the wild in South America.

Feeding your Buenos Aires tetras a varied diet is one of the most important things you can do to give them good health.

Some excellent foods to feed them include:

  • Lettuce
  • Spinach
  • Spirulina flakes
  • Fish pellets
  • Bloodworms
  • Daphnia

When feeding your tetras, allow them to eat all they can in two to three minutes twice per day. Be sure to remove any remaining food to prevent weight gain and dirtying up the water.


Breeding Buenos Aires tetras is both easy and rewarding—a single female can lay up to 2,000 eggs at a time.

Arranging a breeding tank is ideal for your tetra parents-to-be. You should make the water slightly acidic, scatter lots of plants around the tank, and use a sponge filter.

There’s no need two hold back with pairing Buenos Aires tetras for mating; putting a group of them in the breeding tank is effective.

You’ll know that your fish are getting ready to spawn when the females’ stomachs expand with eggs. Since these fish often spawn at dawn, you likely won’t be there to witness it.

However, you’ll be able to see eggs sticking to the plants.

At that point, remove all the adult Buenos Aires tetras. The eggs will then hatch within 24 hours, and they’ll be free-swimming four days after that time.

Common Diseases

Mother nature has created a lot of ways to care for and attack freshwater fish like Buenos Aires tetras. So, while these tetras don’t have breed-specific diseases, they can fall ill with several common tropical fish ailments.

Below are some of the most common diseases you’ll encounter.

Skin Flukes

Skin flukes are a type of flatworm called monogenean trematodes. They’re an uncomfortable parasite for Buenos Aires tetras, feeding on the fish’s skin and causing them to excrete excessive mucus.

Warm water is ideal for skin flukes to breed, so it’s best to turn down your tetra’s water temperature. You can also apply special medication in their water that targets skin flukes and their eggs.


Ich is another type of parasite caused by the protozoan Ichthyophthirius multifiliis. These parasites transfer rapidly between infected fish, and they can live a long time without a host.

Signs of ich include white spots on the body and itching against objects. You can often help Buenos Aires tetras heal from ich if you catch it soon enough and treat the water with anti-ich medicine.

Ammonia or Nitrate Poisoning

Ammonia and nitrate poisoning often go hand in hand because they result from poor water conditions.

Buenos Aires tetras with ammonia or nitrate poisoning go downhill in health quickly. They often develop red spots around their gills and gasp for air at the top of the water.

You should immediately perform a 50% water change if you notice your Buenos Aires tetra has signs of ammonia or nitrate poisoning. Also, check the filter to see if it’s malfunctioning.

Potential Tank Mates

Many fish make excellent tank mates for Buenos Aires tetras. The essential items to remember are that the fish should be of similar or larger size, have short fins, and be fast-moving.

Some outstanding tank mates for Buenos Aires tetras include:

  • Apistogramma
  • Danios
  • Rainbowfish
  • Barbs
  • Dwarf gourami

Whenever you want to introduce new fish to your tetra’s aquarium, be sure to increase the tank size to accommodate extra space and resources.