Fish, Tanks and Ponds

Etymology:

Symphysodon: Greek, syn, symphysis = grown together + Greek, odous = teeth

General Notes:

Despite their size and despite the fact that they are cichlids, Discus are quite timid and delicate fish. They are not fish for the general community tank but require a species tank or a community tank built around their needs.
Once settled and confident they seem much hardier and more relaxed. Ideally their water should be quite soft and acidic - pH 6 to 7 and up to KH 7 for tank bred fish. Wild caught fish should be kept in more sterile conditions where the water chemistry matches their natural environment.
When kept in poor conditions (including the wrong conditions) discus quickly fall ill especially with hole in the head disease. Quite often all that is needed to remedy the disease is a return to the right environment.

Feeding

Wild discus feed on zooplankton, insects and their larva and some vegetation. The diet of fish kept in captivity is somewhat different to this because for years Discus have been fed a diet based on beef heart which has been very finely minced and mixed with other ingredients such has blood worms, blanched spinach, flake food, vitamins and minerals the entire mixture is then frozen and cut in to cubes ready to use. Juvenile Discus grow very rapidly on this diet and often grow larger than their wild counterpart. Discus should be kept in groups of at least six individuals except when breeding when a compatible pair will benefit from having their own tank.
Once the Discus have settled in to their aquarium they will behave far more confidently and can easily be taught to come to you for food.

Compatibility

Tank mates can include small peaceful species which aren't to boisterous, the presence of these small "dither fish" will help to reassure the Discus which will behave in a more extrovert manner as a result. Various sucker mouth catfish are sometimes used as scavengers in Discus aquariums but when these fish grow large they can become aggressive and try to take control of all the food and they have been known to cling to the flanks of the Discus which makes them panic. Brochis make much better scavengers for Discus because they tolerate the higher temperatures better than most species of Corydoras and they are entirely peaceful.

Sexing

There is no reliable way to sex Discus.

Breeding

Discus pair and spawn in typical cichlid fashion by first pairing up and then selecting a spawning site which they will clean and prepare before spawning. But there the similarities end. The way discus care for their young fry is quite different to most other cichlids, once free swimming the fry feed on a special mucus which is secreted from the flanks of their parents. They begin looking for other food after about a week and by two weeks the bulk of their diet is of other things such as micro worms, newly hatched brine shrimps and a very fine blend of the same diet as their parents. With good care growth is very rapid and discus fry can reach 2 - 3 inches in diameter in just 12 weeks.
Discus don't require any spawning triggers to get them to spawn, with good care they will spawn quite freely in soft acidic water.
Aquarium strains of discus may eat their own eggs or fry particularly the first few broods. Eventually most pairs will learn how to look after the brood with out any intervention.

Wild status

Surprisingly the health of wild populations of Discus has not been evaluated. Discus are still regularly caught for the aquarium trade.

Additional information

There is some disagreement about the number and names of Discus species. According to Fishbase there are three species.

• Symphysodon aequifasciatus, Blue Discus.
• Symphysodon discus, Heckel or Red Discus.
• Symphysodon tarzoo