The Buenos Aires Tetra: A Comprehensive Care Guide. Size, Tank Mates & More

The Buenos Aires tetra is a popular freshwater fish that is easy to care for. Learn about the size, tank mates, lifespan, breeding, and more.

Buenos Aires Tetra – Quick Facts

In a rush? Check out the quick facts about Buenos Aires Tetra below.

Fish Info

Scientific NameHyphessobrycon anisitsi
Common NamesBuenos Aires tetra, Buenos Aires fish
AppearanceThe Buenos Aires Tetra has a silver body with a thin blue line starting behind the gills and ending at a black spot in the shape of a diamond on the caudal fin.
DifficultyThe Buenos Aires Tetra is easy to care for, making it an excellent choice for beginner aquarists.
DistributionThe Buenos Aires tetra is found in South America, mainly in the La Plata region in Argentina. However, they can also be found in Paraguay and Brazil.
Lifespan3-5 years
ShoalingThe Buenos Aires tetra is a shoaling fish.
TemperamentBuenos Aires tetras are generally peaceful fish that swim in schools.
Keep in Groups ofAt least 7
Tank Matesblack skirt tetra, serpae tetra, cherry barbs, danios, gouramis, rainbowfish, zebra danios
DietBuenos aires tetras are omnivores and will eat most foods, including flakes, live, and fresh.
LengthThe Buenos Aires Tetra can reach up to 2.75 inches.
Sexual DimorphismMales have brighter, red fins; females are fuller-bodied with a more rounded stomach.
Breeding DifficultyBreeding Buenos Aires Tetras is easy and does not require much care.

Water/Tank Recommendations

Water TypeFreshwater fish.
Water TemperatureThe ideal water temperature for Buenos Aires Tetra is 22 to 26°C (72°F- 78°F).
Water pHThe ideal water pH for Buenos Aires Tetra is 6.5-7.2.
Water HardnessThe ideal water hardness for Buenos Aires tetra is 12 to 35 dGH.
Tank sizeThe minimum tank size for Buenos Aires tetra is 20 gallons. The recommended tank size is at least 25 gallons.


The Buenos Aires Tetras is a beautiful freshwater fish that can bring some much-needed color to your tank. They’re also quite easy to care for, making them an ideal choice for beginners looking to start their first freshwater aquarium.

In this guide, you’ll learn everything there is to know about these fish and how you can help them thrive in captivity. Topics like lifespan, size, habitat requirements, diet, and more!

About Buenos Aires Tetra

The Buenos Aires tetra is a hardy and colorful freshwater fish that can bring a burst of life to your aquarium. Also known as the red-eyed Tetra, this species is beloved by aquarists around the world.

These fish come from South America, and they live primarily in the La Plata region in Argentina. They can also be found in Paraguay and Brazil. You might see them swimming alongside other types of fish in rivers such as Parana or Uruguay.

Buenos Aires Tetras are popular among breeders because they reach maturity quickly and breed easily.


These small fish have an understated silver body with a thin blue line starting behind the gills and ending at a black spot in the shape of a diamond on the caudal fin.

The tailfin has two stripes of red on either side. The blue horizontal stripe begins just behind the eyes and continues across the entire width of their bodies before ending sharply at their tailfin.

Their Length

The average Buenos Aires Tetra size is 2.75 inches in length when fully grown, making them a rather large tetra species that can thrive in larger tanks.


Buenos Aires Tetras can live anywhere from three to five years in captivity. This is a relatively long lifespan for such a small fish, and it’s crucial that you provide them with an excellent environment so they can live their full lifespan.

Even if the fish start out healthy, poor water conditions can shorten their lifespan dramatically. Keep your tank clean and monitor water quality regularly to avoid this possibility.

Sexual Dimorphism

Male and female Buenos Aires tetras are easy to tell apart than other types of tetras due to their distinct markings and vibrant coloration. Males tend to display more brilliant colors than females as well.

Females can be easily identified by their rounder stomachs.

It’s common to find both male and female fish together in one large group, distinguishing them from other species that tend to pair up.


Buenos Aires Tetras are found in shallow waters and often around vegetation. These fish prefer to stick to the shallower parts of the water where there is more plant life to hide in when they are frightened or tired from swimming.

They also tend to migrate with other species, so they may be found throughout their natural habitat.

Buenos Aires Tetras prefer to stay in South America but have been found as far north as Mexico and Canada.

In captivity, Buenos Aires Tetras do well with other similarly-sized fish that are peaceful or active enough to not disturb the still waters.

Caring for Buenos Aires Tetra

Buenos Aires Tetras are an easy-to-care-for species, making them a good choice for beginners and experts alike. However, you should keep the following guidelines in mind to ensure that these freshwater fish live long, healthy lives.

It’s important to remember that Buenos Aires Tetras aren’t fully tropical like some other tetra species (e.g., bloodfin). As such, they do not tolerate warmer waters as well as their tank mates might. This means keeping their water temperatures on the cooler end of the spectrum is paramount if you want them to thrive.


Buenos Aires tetras are omnivores and will eat most foods, including flakes, live foods, and fresh foods. They enjoy a diet rich in protein and vitamins to keep them healthy.

High-protein snacks like bloodworms, brine shrimp, and chopped earthworms can be given occasionally between meals. When hungry enough, they will eagerly devour the food you feed them!

In addition to these occasional treats, Buenos Aires tetras should have a balanced diet that consists of flakes or pellet fish food.

How Often & How Much to Feed Them

Buenos Aires tetras do not require a lot of food to maintain optimum health. Because they are omnivores, you can feed these fish flakes, pellets, and veggies. The fish will snack on algae that grows in the tank as well.

You should introduce some live foods into their diet occasionally too. They like brine shrimp, bloodworms, and other protein-rich snacks.

The fish will show their pleasure over food by swimming in a group and hovering around the tank’s surface. They can become aggressive towards other species that invade their space, so be wary if you see this behavior.

Possible Diseases

Buenos Aires Tetras are not immune to common freshwater fish diseases such as Ich or parasitic infections. The usual health concerns that affect this species are stress-related bacterial infections and fungal issues, which can cause skin flukes and ulcers.

Common symptoms of disease include lethargy, loss of appetite, discoloration of the body, and sores on the surface of the skin. In some cases where there is a sudden temperature change in tank conditions, these fish may exhibit swim bladder disorders.

Tank Setup

Buenos Aires tetras do best in a well-decorated tank with plenty of swimming room. These fish usually live in rivers with tons of vegetation, and they need that feel as close to possible when you’re setting up their aquarium habitat.

Plants are important for these fish, but make sure that your plants aren’t blocking any access to the surface area where they swim and breathe air. They also like dense vegetation around their sleeping spot at night, so you may want several caves or hiding spots scattered throughout the tank too. However, they tend to eat most plants after a while so it is recommended to use more hardy plants for your tank (more on that below).

Aquarium Size

The recommended minimum aquarium size for Buenos Aires tetras is 20 gallons. This should be adequate room to keep these small fish happy and healthy.

However, due to their active nature, we recommend a larger tank if possible. A 30-gallon tank will allow the fish some space to swim freely without disturbing others in the group.

A good rule of thumb is to start by filling the tank with at least 20 gallons of freshwater. Then, for every two Buenos Aires Tetras you plan on keeping, add another 5 gallons or so. Of course, you can always go bigger if your budget allows it!

Buenos Aires tetras are schooling fish and prefer to be kept in groups of 6 or more. A larger tank will help keep the group together (which is important for this species).

Water Conditions

The Buenos Aires Tetra has pretty lenient water condition requirements. While they prefer cooler temperatures (compared with other tropical fish), these fish are not as picky about water quality and pH levels as other species.

The key is to mimic the natural habitat of this species as closely as possible. This includes using slightly acidic water with low carbonate content, which is often found in South American rivers. To achieve this balance, you can use a commercial aquarium salt mix or add potassium bicarbonate to raise the pH level (make sure to test acidity first). If your fish live outside in an area that experiences extreme floods during the rainy season, you could think about setting up a filter system with additional sponging for biological filtration.


The ideal PH level for Buenos Aires Tetra is 6.5-7.2, which helps keep their bodies in prime condition and aids in keeping the water clean by preventing algae growth (a common problem). This can be easily tested with a simple meter or kit (most aquarium kits also have these available).

If you find that your tank’s PH level isn’t at one of the recommended levels, there are steps you can take to adjust it.

The most effective way is to use an ionizer filtration system that neutralizes any chemicals, causing the pH balance to fluctuate before getting into the tank. However, this step alone isn’t enough if your tap water has significant amounts of minerals in it. To ensure your tap water doesn’t disrupt tank conditions, you need to “soften” hard water before starting your filtration system.


Buenos Aires tetras prefer warmer waters. They’re primarily tropical fish and need temperatures no lower than 72 degrees Fahrenheit to thrive.

As a rule of thumb, never drop the water temperature below 68 degrees during winter months or if your aquarium is placed where the air gets very cold (for example, in a room that doesn’t have central heating).

NOTE: If your Buenos Aires tetras start to show signs of stress, such as staying near the surface or spending a lot of time hiding, lower the temperature. A rise isn’t necessary if they seem comfortable.


The recommended hardness level for Buenos Aires Tetra is 12 to 35 dGH. Fish that are not kept in a hard enough environment will experience stress, disease, and even death.

When setting up your aquarium, it’s important to test the water levels before adding these fish. While they should be OK with minor changes (within one or two points), any significant shifts could result in serious harm.

Also, keep in mind that the Buenos Aires Tetra originates from soft water. So, while these fish are not too sensitive to changes in hardness levels, they may prefer a slightly less-aggressive treatment.


Buenos Aires tetras do best in a well-established tank with an efficient filtration system. Although these fish are hardy, they can succumb to ammonia and nitrate poisoning if levels get too high. To prevent this, use a filter that has the capacity to cycle 20 gallons of water per hour.

Also, keep your filters clean. Dirty filters inhibit oxygen production, which can be fatal for Buenos Aires Tetras.

You can use standard hang-on-back filters or an in-tank filter. However, it’s essential to provide plenty of water flow with an in-tank model so that the fish can access oxygenated water whenever they need it. For every 20 gallons of tank capacity, you should have one outlet tube for your filter.

Aquarium Plants

Buenos Aires tetras do well with a variety of aquatic plants. You can use floating or rooted varieties to create the perfect habitat for your fish.

Some good examples include:

  • Java ferns and other broad-leaf plants, which are known for their ability to provide shelter.
  • Anubias, another popular plant that doesn’t spread too much (Buenos Aires Tetras like having lots of open swimming space).

You don’t need an overabundance of vegetation in the tank since these fish spend most of their time at the surface. However, there should be enough room for them to hide among some leaves if they feel threatened.

Behavior and Compatibility

Buenos Aires tetras are peaceful and sociable fish that get along well with similar types of schooling fish. However, they’re not compatible with large or aggressive species.

How Many to Keep Together

These fish swim together in a fast-moving school when in a group. The best way to enjoy them is to keep at least six Buenos Aires tetra together so that you can witness the shoaling behavior up close. If there aren’t enough members in their community, this social creature will become stressed and could experience health problems as a result.

NOTE: You can also consider keeping a single male with two females. This combination is known to be peaceful and stress-free.


Buenos Aires tetra fish are peaceful and non-aggressive with other fish of similar size. They get along with most other types of freshwater fish that have a similar temperament.

These fish will swim in groups throughout the tank, but there will usually be one or two specimens that stick to the lowest parts where plants reside.

The Buenos Aires tetra can be a little shy and will usually stay hidden when startled. However, once they feel comfortable in the environment, their true colors will come out!

Tank Mates

The best Buenos Aires tetra tank mates are other fish of the same species and some similar-looking types. Avoid pairing this fish with larger or more aggressive species that may eat them for food.

You can also keep them with smaller peaceful freshwater creatures like their cousins, the bloodfin tetra or neon tetras. In general, stick to similarly colored tropical freshwater fish that stay small in size. You will avoid potential problems due to aggression and competition over food sources.

Some good examples of tank mates include:


Breeding Buenos Aires Tetra is a straightforward process. You don’t need to worry about selecting breeding pairs or getting the water conditions just right. The sole step you must take is to provide some motivation!

The best way to initiate the breeding process is by lowering the water temperature of your tank and adding more vegetation. This will mimic their natural habitat when they breed, encouraging them to spawn. If that doesn’t work, try reducing the amount of light in your aquarium.

Are Buenos Aires Tetra Fish a Good Choice For Your Tank?

Buenos Aires Tetras are a wonderful freshwater fish that can bring beauty and color to your tank. They’re also quite active, which makes them fun to watch.

Due to the high visibility of this species, they make a great choice for anyone who enjoys watching their tank. We especially like how they swim in groups! Also, the shimmering effect from all those bright blue spots is quite stunning.

Buenos Aires Tetra fish are very easy to care for and will not cause you any problems if you follow the recommended water parameters provided above (there’s no need to be reckless). Overall, these fish are an excellent choice if you want something pretty and low-maintenance.


Buenos Aires Tetras are a beautiful species of fish that bring a lot to the table. With their striking red eyes and coloration, these fish will add some life to your tank!

They’re also quite hardy and can handle many different water conditions very well. This makes them an excellent choice for beginners looking to start their first freshwater aquarium without worrying about keeping conditions just right.

Like many other tetra species, Buenos Aires Tetras don’t require a ton of space to stay healthy (this is something we really like). They won’t grow too large or need tons of horizontal swimming room like so many other popular freshwater fish. This means you can house them in small tanks or keep them with others who have similar needs.


Buenos Aires Tetras do have a few detractors in the fishkeeping community. Some aquarists complain that these fish are more prone to disease than other tetra species.

This is usually due to poor water conditions or an overcrowded tank, which can affect their immune system and overall health. In order to avert this problem, you should prepare your aquarium properly and keep them in a spacious environment.

Another common complaint is that these fish can have a bad attitude. They can be quite aggressive to other species with long fins and will tend to nip them. This behavior usually occurs with long-finned fish, so it’s important to keep Buenos Aires Tetras in their own tank.


Buenos Aires tetras are a fantastic freshwater fish that can add color and activity to any tank. We highly recommend them!

If you have questions regarding the care of these fish, feel free to contact us in the comments below. We’re always happy to help!

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