Paracheirodon innesi

Scientific name:                 Paracheirodon innesi    
Common name:                Neon Tetra
Max. size:                           2.2 cm / 0.85 inches
pH range:                          5.0 – 7.0
dH range:                           1 – 2
Temperature range:         20 – 26°C / 68 – 80°F

The Neon Tetra is an extremely popular aquarium fish. It is sturdy and inexpensive and is often one of the first fish species purchased by beginner aquarists. A shoal of brightly decorated Neon Tetras will add colour as well as activity to the aquarium. Since the Neon Tetras stay quite small and have a peaceful temperament, they are often found in small community aquariums.

Neon Tetra classification:

The Neon tetras belongs to the genus Paracheirodon in the family Characidae. This makes it closely related to other popular aquarium fishes like the Cardinal tetra (Paracheirodon axelrodi) and the Green Neon tetra (Paracheirodon simulans). The less commonly kept Black Neon tetra (Hyphessobrycon herbertaxelrodi)is however a more distant relative since it belongs to another genus within the family Characidae; the genus Hyphessobrycon.
All members of the genus Paracheirodon are native to the Neotropic ecozone in northern South America and their bodies are decorated with a characteristic sparkling blue lateral line. They are often kept together in planted community aquariums with soft, acidic waters and tropical water temperatures.

Neon Tetras in the aquarium trade

The Neon tetra is an extremely popular aquarium fish, especially among beginner aquarists. Over 1.5 million Neon tetras are imported to the United States alone – each month! It can be tricky to breed in captivity for hobby aquarists, but professional breeders that produce immense quantities of Neon tetra exist in several countries world wide. If you purchase Neon tetras in the United States, the chance is high that they hail from Thailand, Singapore or Hong Kong. Wild caught Neon tetras from Brazil, Colombia and Peru are however also still available in the trade.

Neon Tetra habitat and range:

The Neon Tetra is a pelagic freshwater fish native to tropical parts of northern South America. The Neon tetra originates from westerns Brazil, south-eastern Colombia and eastern Peru and wild Neon Tetras can be found in the headwaters of the River Amazon, Tiger, Napo and Yarapa. It is present in both blackwater and clearwater stream tributaries. You can however not find Neon tetras in the whitewater rivers that run from the Andes. The Neon Tetras have bright colours and an iridescent stripe in order to be visible in dark blackwaters.

A lot of Neon Tetras are caught from Rio Solimões. Rio Solimões is a name attributed to an upstream part of the great River Amazon; a part that starts at the border of Brazil and Peru and ends when the river converges with Rio Negro. (In Brazil, the name Rio Solimões is sometimes used even further upstream, but the name Rio Marañón is more common for those parts.)

The South American blackwater and clearwater streams and rivers have very soft and somewhat acidic water. The flow through tropical regions and the water temperature stays around 20 – 26° C (), sometimes higher. The commercial bred Neon Tetras have often been adapted to conditions that are very different from those found in their native habitat.

Today, an introduced population of Neon Tetra is established in Singapore.

Neon tetra description:

Just like the other tetra species, the Neon tetra has a spindle shaped body and a blunt nose. A glistering blue line runs along each side of the body, from the nose and all the way to the adipose fin. The Neon tetra is also decorated with a red stripe that runs from the middle of the body to the base of the caudal fin. The side over the blue stripe is of a dark olive green shade. The belly is of a silvery colour and the anal fin is nearly transparent.

During the night, when the fish is resting in a sheltered place, the sparkling colours will be turned off and the fish will look dim. If you quickly turn on the lights in the aquarium after a longer period of complete darkness, you might not notice your Neon Tetras at first. If the colouration continues to be dull even after some time in the light, your tetras might be ill or stressed. You might also be keeping them on an inadequate diet.

The Neon Tetra is often mixed up with the Cardinal Tetra, since they both feature striking red and blue stripes. The Cardinal Tetra is even sometimes referred to as “Red Neon Tetra” in everyday language, even though it is in fact a separate species and not a colour variation of the Neon Tetra. Distinguishing these two species from each other is however not difficult at all if you know what to look for. Under the sparkling blue stripe, you will see a red lateral stripe in both species. If this red strip ends roughly halfway from the nose of the fish, you are looking at a Neon Tetra. If the striping instead continuous much longer, you are looking at a Cardinal Tetra. The name Cardinal Tetra is derived from the long, red robes worn by cardinals and these robes do not end half-way.

Neon Tetra behaviour and suitable tank mates:

The Neon Tetra is a peaceful fish that is often kept in community aquariums with other non-aggressive fish species of roughly the same size. Neon tetras look very beautiful when combined with other tetra species, but they can be combined with fishes from a broad range of other families as well. Keep in mind that most tetra species are less robust than the Neon tetras when it comes to water conditions. Neon tetras should naturally never be combined with larger fishes that will consider them prey, or aggressive fish species that will bully them.

The Neon Tetra is a shoaling species and you should always keep at least five Neon Tetras together, preferably more. A Neon Tetra that is kept alone will be much stressed and spend most if its time hiding. The stress can also weaken its immune system and make it more susceptible to illness. A large group of Neon Tetras are naturally also much more beautiful to watch in the aquarium and you will be able to see a much broader range of natural Neon Tetra behaviors. When kept in a shoal, Neon tetras are active creatures and they will spend most of their time in the middle to lower strata of the aquarium. Neon Tetras are known to sometimes shoal together with the closely related Cardinal Tetras.

Neon tetras can reach an age of 10 years or more in captivity, but most Neon Tetras have considerably a shorter life span than this.

Neon Tetra setup:

Try to mimic the natural Neon Tetra habitat when you set up the aquarium. The River Amazon and its tributaries are filled with densely grown plant life and the rivers and streams are shaded by jungle vegetation. Your Neon Tetras will therefore appreciate a planted aquarium with plenty of hiding spots. There should also be an open area for swimming. The light should be subdued; ideally use floating plants to make the aquarium a little darker for your tetras. The bottom should preferably consist of a dark substrate. Many aquarists cover the back and sides of the aquarium with dark tissue to make the aquarium darker and bring out the contrasting colours in their Neon Tetras. The recommended minimum aquarium size is 60 cm (24 inches).

Neon Tetra care:

Captive bred Neon Tetras are often adapted to conditions that differ a lot from those found in the original Neon Tetra habitat. Wild Neon Tetras inhabit very soft and slightly acidic waters in tropical regions of South America where the water temperature usually stays between 20 and 26° C (68 and 80° F). Rainforest rivers and streams are frequently replenished by soft downpour and frequent water changes are therefore recommended in the aquarium.

Generally speaking, the recommended pH range for Neon Tetras is 5.0 – 7.0 and the recommended dH range 1-2. If your Neon Tetras have been raised in an aquarium with different water chemistry, a rapid change can however harm them. Neon Tetras should therefore always be gradually adjusted to new conditions.

Since Neon Tetras are so popular, the Neon Tetra breeding business has naturally attracted not only dedicated Neon Tetra breeders but also irresponsible ones that do not really care about creating high quality fish. A lot of the commercially bred Neon Tetras will end up in aquariums kept by novice aquarists that will assume that they have done something wrong when their Neon Tetras die shortly after being purchased. Selling low quality Neon Tetras is therefore not really risky; it can even be a good for business since many inexperienced aquarists will return to the store for more and more Neon Tetras as the old ones succumb. This is naturally a problem since you might get really fragile Neon Tetras from your local pet shop that will not adapt well to new conditions. It is therefore always recommended to provide your Neon Tetras with plenty of time to acclimatize themselves when you introduce them to their new home. Carefully monitor your Neon Tetras and quickly remove dead specimens before they get a chance to contaminate the water.

It is perfectly natural for a Neon Tetra to look dull during the night since it turns off its iridescent colours. In the morning, it can need a little time to recover. If your Neon Tetra continues to show dull colours throughout the day you should however try to figure out why, since it is a warning sign that your fish is not doing well. A Neon Tetra that is kept alone instead of in a shoal can loose its iridescent colours, and the same is true for tetras that become stressed by the presence of bullying fish or that are kept in a barren aquarium without any good hiding spots. It can also be a sign of disease, poor water quality or malnutrition.

Neon Tetra feeding:

Wild Neon Tetras are omnivore and feed on plant matter as well as on crustaceans, worms and small insects. They are not fuzzy eaters in the aquarium and will accept most food types, including flake food, frozen food and freeze-dried food. Keep them on a varied diet to prevent malnutrition. You can for instance use a high-quality tropical flake food as a base and supplement it will occasional treats in the form of daphnia, brine shrimp, bloodworms or similar.

Neon Tetra disease:

Neon Tetras are susceptible to the Neon Tetra disease. There is still no available cure for this disease and it will often kill the fish. Neon Tetra disease is caused by a sporozoan named Pleistophora hyphessobryconis. The disease is therefore also known as “Pleistophora”.

During the initial stage of Neon Tetra disease, parasite spores enter the Neon tetra. Common symptoms include restlessness and dull colouration. As the disease proceeds, cyst will develop and the fish body can become lumpy. The Neon Tetra will often have trouble swimming and towards the final stages of the disease the spine can become curved. The weakened fish is also susceptible to secondary infections.

As mentioned above, these is still no cure for Neon Tetra disease and trying to prevent the parasite from entering your aquarium in the first place is therefore the best course of action. The parasite is typically introduced via live food or newly purchased fish. By cultivating your own live food you will gain a greater control over what you put in your aquarium. Brine shrimp is for instance very easy and hassle-free to cultivate at home. When you purchase new fish, you should ideally keep them quarantined in a separate aquarium and look out for signs of illness. In the aquarium, fish often catch the disease when they eat dead fish. Removing sick and dead fish as soon as possible is therefore important. Some aquarists report that using a diatom filter decreases the risk of Neon Tetra disease, but it is only a supplement, not a substitute for the precautions described above. A diatom filter can reduce the amount of free parasites in the water.

There is also a disease known as “false Neon Tetra disease” that is often confused with true Neon Tetra disease. This disease is not caused by a sporozoan; it is caused by bacteria. The symptoms are however very similar and unless you have access to a laboratory it will be virtually impossible for you to tell the difference between the two diseases.

Neon Tetra breeding:

Wild Neon Tetras are highly prolific and have a minimum population doubling time below 15 months. They are egg-scatterers and do not engage in any parental care.

In captivity, Neon tetras are considered quite difficult to spawn, especially among hobby aquarists since it can be hard to achieve perfect water conditions. A majority of the Neon Tetras found in pet shops are therefore wild caught or commercially bred by large Neon Tetra breeding companies. It is possible for Neon Tetras to spawn every two weeks.

Sexing Neon Tetras can be hard, but the female usually have a bigger and rounder belly than the male. The blue line will be straighter in males, while the round female body creates the impression of a bent blue line. When she is ready to breed, her body will become very broad since she is filled with eggs.

If you want to breed Neon Tetras, you should ideally set up a separate breeding aquarium from which the parents can be removed as soon as the eggs have been fertilized. To reduce the risk of illness in eggs or fry, you can sterilize all items that you place in the aquarium.  The breeding aquarium should be equipped with a lid, since Neon Tetras can jump really high during the breeding period. The bottom of the aquarium should ideally be covered in 2-3 inches of rock. Include fine textured aquatic plants in the set up. Keep the water temperature below 24° C (75° F). The hardness should always be below 4 degrees, ideally in the dH 1-2 range.

If you want to obtain high-quality fry, it is important to only let high-quality adult fish breed. Old or unhealthy fish should not be bred. Place a pair of Neon Tetras in the breeding aquarium and feed them plenty of live food to induce spawning. Mosquito larvae are used by many professional breeders. Some breeders will let the nitrate level rise quite high in the breeding aquarium before they change at least 50 percent of the water since this sometimes induces spawning. The rapid decrease of soluble waste is a way of mimicking a fresh, replenishing rain. The breeding aquarium should be dark at first, and you can then gradually increase the lighting until the couple spawns. (Neon Tetra eggs are a bit light sensitive so it is important to limit the amount of light after spawning.)

Neon tetras will usually spawn during early morning and the parent fish should be removed from the breeding aquarium as soon as possible after fertilization since they will not hesitate to eat their own offspring. In aquariums, a normal batch will consists of approximately 130 eggs but only a smaller number will turn into fry. Neon Tetras that spawn in aquariums are usually not very prolific, so do not expect more than 40-50 fry even from a good spawning.

Neon tetra eggs are somewhat adhesive and will often stick to the surface of aquatic plants. They are nearly transparent when they have just been released, and will hatch after 22-30 hours. It will take the fry 3-4 days to become free swimming.

Neon Tetra fry are very small and must be provided with miniscule food, such as infusoria, rotifers or egg yolk. After 1-4 weeks, they will be large enough to eat newly hatched brine shrimp. Large fry will appreciate shaved cattle liver. When the fry is roughly one month old, they will start displaying their adult colouration.