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Buenos Aires Tetra – Hyphessobrycon anisitsi

Buenos Aires Tetra

Tetras are amongst the most popular aquarium fishes. There are probably more than 150 distinct species of tetra from which the aquarist may choose and this includes a large number of visually stunning fishes that are bound to enhance any home aquarium.

Is the Buenos Aires Tetra a good community fish? The Buenos Aires Tetra should be considered to be an excellent community fish and gets on with most species. It is reputed by some to be something of a fin-nipper so avoid keeping it with elaborately-finned species (Guppies, Angel Fish, male Bettas, etc.). 

Key Facts

CategoryKey Facts
Common name(s)Buenos Aires Tetra
Scientific nameHyphessobrycon anisitsi
Originate fromLa Plata region of Argentina, Paraguay, and southeastern Brazil in South America
Care requiredEasy to care for and hugely popular
TemperamentPlacid, shoaling fish
Colour & FormBlood-red Caudal, adipose, dorsal, pelvic and anal fins; streamlined, silver body with greenish tinge along spine, black, flattened diamond shape along spine from adipose fin to rear of caudal fin; orange, fading to yellow crescent over eye, above pupil
LifespanUp to 5 years
Adult size3 inches
DietOmnivorous – eat aquatic insect larvae in nature
Aquarium size36 inches in length or greater
Compatible withMost other Tetras, Barbs, Danios, female Guppies and other livebearers, dwarf cichlids, smaller Gouramis, catfish and loaches
Avoid keeping withSlow- moving species with elaborate finnage
BreedingEasy if you put the fish in the right environment.
Water temp64 to 82 Fahrenheit
Water pH5.5 to 8.0
Water hardness (dGH or dH)1 to 18 dGH

Origins of the Buenos Aires Tetra

Tetras, as a “family” of fishes belonging to the biological family Characidae are found in nature in Africa, Central America and South America.

The Buenos Aires Tetra originates in the La Plata region of Argentina, Paraguay, and southeastern Brazil in South America. The vast majority of Buenos Aires Tetras available to aquarists are captive-bred. 

Characteristics of the Buenos Aires Tetra

As you can see, the Buenos Aires Tetra is an elegant and streamlined fish. It will grow to up to 3 inches in the aquarium and live for around five years. 

The Buenos Aires Tetra is an active swimmer, always on the move. The Buenos Aires Tetra has a silver, streamlined body. 

The dorsal, caudal anal, pelvic and adipose fins can be blood red in colour – particularly the caudal fin – and strong fin colouring is an indicator of good health.  If you look around the spine of the adult fish, then you will note a greenish tinge to the scales stretching back to the black, flattened diamond shape which starts just before the adipose fin and stretches to the rear of the caudal fin with the top and bottom of the flattened diamond at the root of the caudal fin.

The upper half of the eye is distinctive in that it has a crescent which is orange in the top, central area fading to yellow just above the centre of the eye, either side of the pupil to the left and right.

The adult male may have more vibrant colouring than the female whilst the female may have a fuller body and, once gravid (carrying eggs) will become even more rounded and, at that stage, is even more easily distinguished from the male.

Buenos Aires Tetra

The Buenos Aires Tetra tends to inhabit the middle area of the aquarium (top to bottom). That said, it is a vigorous fish when breeding and will readily traverse the entire aquarium.

The Buenos Aires Tetra is, by nature, a shoaling fish and it is generally recommended to purchase six or more fish, as their nature is to swim together as a shoal and they will tend to thrive much better as a shoal. Buenos Aires Tetras do have a reputation for being fin-nippers so it would be best not putting them together with long-finned species such as Guppies, Angel Fish, male Bettas or other elaborately-finned species.

Whilst it is typical to keep at least six Tetras in an aquarium it is generally recommended to keep ten or more Buenos Aires Tetras, as they tend to thrive better. It is also suggested that if the temperature of the water is higher in the given range then the colouring of the red fins is more striking. That said, water at a higher temperature tends to shorten the lifespan and many aquarists find that the Buenos Aires Tetra is most adaptive and can tolerate a wide range of water conditions and temperatures whilst maintaining peak condition.

Buenos Aires Tetras prefer a shaded tank so consider including floating leaves and/or allowing vegetation to grow so that it floats on the surface of the water to provide shade.

It is generally advised that the minimum tank size for Buenos Aires Tetras should be one of 36 inches in length or more due to the active nature and size of the species, which will enable a small shoal to move around freely. The tank should be well-planted but with clear areas where the fish can swim freely. The water should have gentle movement.

Some aquarists report that their Buenos Aires Tetras devour their plants, other than the Java fern, whilst others report that these fish don’t bother their plants at all. Being a very active swimmer, I believe it likely that the Buenos Aires Tetra will eat plants if it is underfed and it will burn off much more energy than slower-moving species so feeding your shoal more will probably make the difference.

It is worth noting that the Buenos Aires Tetra is a much larger species than, say, the Neon Tetra so ensure, as suggested above, that your shoal lives in a large enough tank.

Buenos Aires Tetras prefer fairly neutral water with a pH of 5.5 to 8.0, cooler than many tropical species; from 64 up to around 82 Fahrenheit and up to 18 dGH.

The general rule for Tetras is that by keeping six or more of the same species in an aquarium they will be fully aware of which is male and which is female and they will act accordingly.

Most (but not all) Tetras have an additional fin which identifies them as being Tetras and the Buenos Aires Tetra is no exception. If you look between the dorsal fin and the caudal (tail) fin of the Buenos Aires Tetra you will observe a tiny, additional fin, known as the adipose fin. The purpose of this fin is not fully understood but, if it is present on a freshwater tropical fish then you can be pretty certain that the fish is a Tetra.

Tetra comes from the Greek word “Tetragonopterus” which means square-finned and appears to relate to the four fins on vertical plane of the fish (dorsal, adipose, caudal and anal fins) which span the central line of the fish (when viewed from above or below, front or rear) and are not present as a pair (e.g. the pectoral or pelvic fins).

Buenos Aires Tetra – Video

How do Buenos Aires Tetras breed?

Tetras, in general, will scatter eggs by laying them over fine plants such as Cabomba, Fontanalis or Java Moss.

Buenos Aires Tetras, like most species, are noted to leap above the water surface during breeding and in general, so it is advised that the tank should be covered to mitigate the risk of losing fish.

As the female Buenos Aires Tetra becomes ripe with eggs, the difference between the sexes becomes even more evident. If you plan to attempt to breed Buenos Aires Tetras then it is recommended that you have a breeding tank prepared. Such a tank can be empty but you may wish to include a mesh or grid under which the fertilized eggs will fall.

That said, Buenos Aires Tetras will breed in a community tank and, if the tank is well planted, it is likely that at least a few fry may survive to reach adulthood.

I have observed Buenos Aires Tetras breeding readily and vigorously in quite neutral water but slightly acidic water is the general recommendation

The female will swim vigorously around the tank and, if you include two males then they will encourage her to lay her eggs by bumping into her. She will lay her adhesive eggs which will immediately be fertilized by the male(s) and will either stick to plants or will fall to the bottom of the tank (preferably through the mesh or trap). Once spawning is complete, remove the adults, as they are likely to consume the eggs, given the chance, and take no further parental responsibility.

Spawning usually takes place in the early morning.

Breeding tank for Buenos Aires Tetras

You should prepare a tank of around 20 gallons in size with mature water. The water should be at a pH of around 6.0 to 6.8, a dGH of 18 and, ideally around 78 degrees Fahrenheit with a low level of light.

You may wish to introduce mosquito larvae or bloodworm as an inducement to reproduction.

The female will swim amongst the plants, laying her eggs whilst the male will swim alongside or behind her and fertilize the eggs as they are laid. Typically, the female can lay as many as 2,000 eggs during a spawning, which will adhere to plants or will sink to the bottom of the tank.

Once the female has scattered her eggs and the male has fertilized at least some of them then the adults should be removed carefully from the breeding tank because they will have nothing more to do with the eggs but they may simply eat them.

Keep the lights off and the tank dark because Tetra eggs and fry are particularly sensitive to the light.

The eggs will hatch typically in a day or so depending on tank temperature and conditions and the fry will become free-swimming after around three to four days after hatching. Keep the tank unlit for the first week or so then gradually increase the lighting.

The newly hatched fry will firstly feed from their yolk sac but, once free-swimming, can be fed infusoria (particularly rotifers) and will also thrive on egg yolk during the first two to four weeks. It is worth mentioning that immediately after hatching, fry seem quite vigorous but will soon go into a resting state before they become free-swimming so please don’t mistake this initial stage as being free-swimming.

After around four days or so add baby brine shrimp. Once the fry are sufficient in size not to be treated as a snack then they can be introduced into the community tank where they will join the existing shoal. Before moving the adolescent fish into the community tank ensure that you have balanced the water temperatures to mitigate the risk of White Spot or other diseases being triggered.

Should your Buenos Aires Tetras have a special diet for breeding?

Adult Buenos Aires Tetras don’t need any particular inducement to breed. That said, it has been suggested that adding mosquito larva may encourage them, presumably because the addition of a new food may “fool” the fish into thinking that it is breeding time. From my own experience, I would always recommend keeping all of your fish in the best possible condition at all times, as this is good for the wellbeing of your fish.

Mike Wheeler

I started keeping freshwater tropical fish in 1972 and it has been something of a passion ever since. In this website, my aim is to build up an everyman's guide to help the everyday aquarist get the best from this inspiring and entertaining hobby.

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