Cardinal tetras in your fishtank: how to keep the popular aquarium fish

Cardinal tetras in your fishtank: the popular neon fish at a glance

Cardinal tetras are probably the most popular tetras in aquarium history. No wonder you bring, thanks to its unique shimmering blue-red painting, a colourful mood into every fishtank. The cardinal tetras are not only handsome, but also easily become friends with typical us water values and are very easy to socialize with other species. However, it is important to distinguish the Cardinal tetras from the very similar red neon tetras and the blue neons. Especially the blue neon looks for colder basins and the neon tetra defines territories and defends them. Both types are therefore not exactly the best candidates for every community fishtank. The three species differ by just a half or a whole red line and therefore it is not surprising that badly informed aquarists quickly turn to the wrong species and become unhappy with it. In the following article we provide you a lot of information about keeping, demands on water and breeding Cardinal tetras.

Table of Contents

How do Cardinal tetras, blue neon tetras and neon tetra differ optically?

Apart from the behaviour, the optical differentiation of the fish is the most striking difference:

  • Cardinal tetra: solid red bar (under the blue bar)
  • Red Neon tetra: half red bar (under the blue bar)
  • Blue neon tetra: no red bar (under the blue bar)
Keep Cardinal Tetra in your fishtank

Where do Cardinal tetras occur?

Cardinal tetras have a very wide area of processing, which reaches over Venezuela (Orionko), Brazil (Rio Uaupés and Rio Negro tributaries from the north and east) up to Western Colombia's black water. Animals escaping from export stations are often found in the streams around Manaus.

What water values and temperature do Cardinal tetras need?

Cardinal tetras are comfortable with the following water conditions:

Temperature: 23°C-27°C
pH-Value: 5,0 - 7,5
Water hardness: 3-14 °GH

The optimum pH value is 5.8, but can vary between 4 and 7.5. The water should be very soft in the best case, around 5 °GH would be a desirable value, but the total hardness can also be between 3 and 14 °GH. In addition, the water should contain as few Ca² and Mg² ions as possible. Too hard water, rich in minerals, can easily cause damage to the animals.

How do you keep Cardinal tetras?

It is still believed that the Cardinal tetra is a black water fish, but this is not true. In nature the fish prefers biotopes in the clear water and stays there in shaded areas. One can almost speak of a phobia of light, especially for young animals. The tank should therefore not be too brightly lit, this can be achieved on the one hand by weaker fluorescent tubes/LED's or quite simply by floating plants and decoration, such as big wood roots.

The Cardinal tetra is otherwise a very peaceful small swarm fish, which is suitable for every community fishtanktank that meets its demands on the water. It will be about 5cm long and should be kept in groups of 8 animals or more. Please note that for keeping the fish you need at least a 15-20 gallon aquarium (24 inches in length). Interestingly, the Cardinal tetra forms groups with other tetra species, e.g. with the lemon tetra. However, it makes more sense to socialize it with species, which inhabit other tank regions, so that the fish do not get in their way and have enough space to swim. The Cardinal tetra gets along very well with dwarf cichlids (like ram cichlid or cockatoo cichlids) but also with small gouramis. (click here for more setting examples). Of course, its small size and its distinctive colouring should be taken into account, which easily leads larger fish to eat Cardinal tetras. If you still want to socialize the animals with much larger species such as discus or scalars, you should first add adult neons and then the larger young animals then there is usually no danger.

Cardinal tetras are best seen in densely planted basins with dark ground. They feel particularly at home in such densely planted basins with fine-grained plants. As this fish is very is known for swimming a lot, sufficient swimming area should be provided. In this article we mention a minimum tank edge length of 24 inches, which usually corresponds to a volume of 15-20 gallons, but the animals should best be kept in tanks from 36 inches length (50 gallons). In this case, the animals swim within big schools which looks very nice.

Keep Cardinal Tetra in your fishtank

What does the Cardinal tetra eat?

The Cardinal tetra is essentially a predator of white, red and black mosquito larvae, artemia and many other live and frozen foods. Red neon tetracan also be fed with dry food. Nevertheless, care should be taken to feed life or frozen food at regular intervals, as this can have a positive effect on his well-being and his colouring, among other things.

How do you breed Cardinal tetra?

Cardinal tetras need very soft water for breeding. A total hardness of 1-2 °GH and a pH value of 5.0 - 6.0 are absolutely necessary. The water temperature should be around 24°C. Breeding is only possible in rounded basins. The process: With the spawn-act, the male sling around the female almost completely, whereby the female stands almost vertically in the water. Afterwards the female lays up to 130 eggs between fine, slow-growing plants. After spawning, the breeding pair is removed; the eggs must remain darkened, otherwise they will fungus. After about 24 hours the young Cardinal tetras hatch and are free swimming five days after. The young should be fed with small paramecium such as Artemia nauplii.

More facts about the Cardinal tetra:

Even today, every single Cardinal tetra is a tomboy. The animals are difficult to breed, which makes this type of procurement particularly inefficient to this day. Because the fish therefore have to travel a long way from South America to the US, they usually arrive in our aquariums in poor condition. It is not unusual for some of the animals to fall out in the first few days. In general, Cardinal tetras are hardly susceptible to disease when kept in good conditions and can live for up to 8 years.


The Cardinal tetra is the most sold and popular aquarium fish in the US. It can be found in many aquariums, which is not least due to its fascinating blue-red appearance, which embellishes every aquarium. It is also a quiet and peaceful aquarium fish that is easy to socialize with other species. His demands on water are usually associated with typical us water parameters. It's not hard to keep the Cardinal tetra.

Cardinal tetra in a video

Cardinal tetras in your fishtank: how to keep the popular aquarium fish

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