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Hyphessobrycon herbertaxelrodi

Black Neon Tetra




Known only from the Brazilian section of the Rio Paraguay drainage. As with most of the commonly available tetras, you’ll find it difficult to acquire wild specimens, though. Virtually all fish entering the trade are commercially bred on farms. Most of the ones on sale in the UK originate from Eastern Europe or the Far East.


Small tributaries, creeks, areas of flooded forest and sand banks. The water in these biotopes is often stained brown with tannins and other chemicals released from decaying organic material, and is very acidic as a result.

Maximum Standard Length

1.6″ (4cm).

Aquarium SizeTop ↑

A standard 24″ x 15″ x 12″ (60cm x 37.5cm x 30cm) – 70 litre tank is big enough to house a small shoal.


As it’s commercially bred in such huge numbers, it is adaptable and will thrive in most well-maintained tanks. It does look particularly effective in a heavily-planted setup, though, and can appear a little washed out the decor is too sparse.

If you really want to see it at its best, you could set up a biotope tank. Use a substrate of river sand and add a few driftwood branches (if you can’t find driftwood of the desired shape, common beech is safe to use if thoroughly dried and stripped of bark) and twisted roots. A few handfuls of dried leaves (again beech can be used, or oak leaves are also suitable) would complete the natural feel. Allow the wood and leaves to stain the water the colour of weak tea, removing old leaves and replacing them every few weeks so they don’t rot and foul the water. A small net bag filled with aquarium-safe peat can be added to the filter to aid in the simulation of black water conditions. Use fairly dim lighting. Under these conditions it will develop its most intense colouration.

Water Conditions

Temperature: 74-82°F (23-28°C)

pH: 5.5-7.5. Although it will survive in slightly alkaline water, it tends to be more colourful when kept in acidic conditions.

Hardness: 2-15°H


Easy to feed. It will readily accept just about anything offered. For the best condition and colours, offer regular meals of small live and frozen foods such as bloodworm, Daphnia and brine shrimp, along with dried flakes and granules.

Behaviour and CompatibilityTop ↑

One of the best tetras for the ‘general’ community setup. It is lively, peaceful and its colours offer a pleasing contrast to those of many other species. It’s a good tankmate for most commonly available livebearers, danionins, rasboras, other tetras and peaceful bottom dwellers such as Corydoras or smaller Loricariids. It can also be kept with the majority of commonly available gouramis and dwarf cichlids. Obviously, it isn’t safe with larger species that may see it as food. In a biotope tank as described above, it can be combined with Hemigrammus or other Hyphessobrycon species, pencil fish, Apistogramma dwarf cichlids and the aforementioned bottom dwellers.

Always buy a group of at least 6 of these, preferably 10 or more. It is a shoaling species by nature, and will fare much better when in the company of its own kind. It actually looks far more effective when maintained like this anyway.

Sexual Dimorphism

Mature females are more rounded in the belly than males, and tend to grow a little larger.


Quite easily bred, although you’ll need to set up a separate tank in which to do so if you want to raise any numbers of fry. Something around 18″ x 10″ x 10″ in size is fine. This should be very dimly lit and contain clumps of fine-leaved plants such as java moss or spawning mops, to give the fish somewhere to deposit their eggs. Alternatively, you could cover the base of the tank with some kind of mesh. This should be of a large enough grade so that the eggs can fall through it, but small enough so that the adults cannot reach them. The water should be soft and acidic in the range pH 5.5-6.5, gH 1-5, with a temperature of around 75-80°F. Filtering the water through peat is useful, as is the use of RO water. A small air-powered sponge filter bubbling away very gently is all that is needed in terms of filtration.

It can be spawned in a group, with half a dozen specimens of each sex being a good number. Condition these with plenty of small live foods and spawning should not present too many problems.

Alternatively, it can be spawned in pairs. Under this technique, the fish are conditioned in male and female groups in separate tanks. When the females are noticeably full of eggs and the males are displaying their best colours, select the fattest female and best-coloured male and transfer them to the spawning tank in the evening. They should spawn the following morning. Interestingly, during the act itself the pair often turn completely upside down.

In either situation, the adults will eat the eggs given the chance and should be removed as soon as eggs are noticed. These will hatch in 24-36 hours, with the fry becoming free swimming a 3-4 days later. They should be fed on an infusoria-type food for the first few days, until they are large enough to accept microworm or brine shrimp nauplii. The eggs and fry are light sensitive in the early stages of life and the tank should be kept in darkness if possible.

NotesTop ↑

This species is ubiquitous in most dealers’ tanks and is one of the best choices for the newcomer to fishkeeping, being both hardy and inexpensive. It’s been deservedly popular in the hobby for several decades. Despite the common name, it’s not a particularly close relative of the neon tetra, which belongs to the genus Paracheirodon. It’s sometimes confused with the similar looking flag tetra, H. heterorhabdus, but is easily distinguished as it lacks the upper, red lateral stripe of its relative.

As with the closely related Hemigrammus, the taxonomic status of all species in the genus Hyphessobrycon is currently Incertae Sedis, meaning uncertain. The genus is currently used as something of a catch-all for over well over 100 species of small characin. Most experts agree that a full revision is required, with the likely outcome that many species will be placed into new or different genera.

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