Named after their distinctive body shape, the discus was originally described by a Dr. Heckel back in 1840, whose name is commemorated by Heckel’s discus (Symphysodon discus). The green discus (S. aequifasciatus) occurs further west in the Amazon basin, with Heckel’s discus being found mainly in the Rio Negro, but when these fish come into contact, so they will hybridise together.

The third recognised species - S. tarzoo - in to be found to the west of the port of Manaus, near the mouth of the River Amazon. It has also been suggested that there is a fourth species, known as the common or blue or brown discus (S. haraldi), but this may just be a regional form of the green discus.

Space needs

A large tank, measuring about 48in (120cm) long and 15in (40cm) deep, will be needed to house several of these fish. Include plenty of tall plants, allowing the fish to weave through these with their narrow bodies, just as they do in their natural habitat. Adults will grow to 20-25cm (8-10in) in terms of their length and height.

Care requirements

If you are frustrated chemistry student, here’s your chance. In terms of water chemistry, discus need soft and acidic water, around 10-15°DH and with a pH reading of 6.0, so you can play around with items such as water softeners, pH meters and test kits as necessary, to your heart’s content. Make sure the water conditions are suitable and the aquarium is established before you acquire the discus.

Water temperature in the aquarium should be maintained in the range of 28-31°C (82-88°F), monitored with a thermometer. Be sure to use a heater guard, not just to prevent any risk of the fish burning themselves on the heater, but also, to prevent the females laying eggs here in due course. Discus require a diet of small live food, and can be persuaded to eat freeze-dried or other prepared foods of this type, with a range of specialist diets available for them.


Usually kept together in shoals on their own, rather than being mixed with other fish. They rarely fall out with each other and look very graceful when housed in this way. Provided their needs in terms of water chemistry can be accommodated, then discus can be kept and bred without undue difficulty. They should ideally be accommodated in tanks only with others of their kind.

These fish normally live in shoals, and then once a pair bond is obvious, the discus concerned should be moved to separate accommodation for spawning purposes or the other fish transferred elsewhere. Unfortunately, there is no easy way of sexing them.


The four founder bloodlines from different parts of the Amazon have all contributed to today’s colour varieties. Discus kept in aquaria today are all much brighter and more vividly-patterned than their wild counterparts. This trend began in Germany, where brilliant blue discus of various types were originally created.

Now Asia has become a hot-bed for discus breeding, and it is here that many of today’s popular varieties such as the grotesquely-named pigeon blood, with its reddish colouration (left), have been created. It’s not just colouration either - patterning counts too. There’s the snakeskin discus (below) for example, so-called because of the wavy patterning on their bodies resembles the markings of snakes.

The cost of discus tends to be based both on their size and the relative rarity of the variety concerned. Young fish are less costly to acquire than adults, and proven pairs fetch more than individuals


There is no easy way to sex these fish, other than by their behaviour. In a group, a pair will remain close together, nuzzling each other. They can be moved to separate accommodation for spawning purposes or the other fish in the aquarium should be transferred elsewhere. As the time for spawning approaches, so both members of the pair will clean the chosen surface for the eggs, which may be a broad leaf or rock work.

A female discus can lay 200 or more eggs, but be prepared for initial disappointment, as sometimes, the adult discus will eat them soon afterwards. This is quite common behaviour in young pairs breeding for the first time, and they should hopefully do so without any problems when they spawn again in the future. Keeping disturbances to a minimum at this stage will enhance the chances of success.

About two days after egg laying, the adult fish will help to free the young from the egg cases, and attach them to aquatic plants. By the age of five days old, the fry will be swimming and remain close to their parents. At this stage, the young discus are elongated in shape. They gradually start to assume their characteristic disc-like appearance from the age of three months old. It will take a further six months, however, for their coloration to develop fully.

Did you know?

These fish show remarkable parental care. Once the eggs have been laid, the pair guard them, driving away would be predators. After hatching, the young discus are then fed by their parents, on a special secretion called ‘discus milk’. This is produced on the sides of their bodies, with the young fish nibbling here to obtain the nutrients. Studies have revealed that discus milk also contains immunoglobulins - helping to protect the young fish against infections early in life.


Averages around 10 years.

Likely illnesses

Can suffer from hole-in-the-head disease, which is a nasty parasitic illness caused by unicellular protozoa called Hexamita that attack the forehead, and is likely to cause permanent scarring. As it name suggests, a series of holes start to develop in the vicinity of the head. Luckily, it can be treated successfully if caught in time with suitable medication.