Description
The discus is the fish many hobbyists picture when they start out, and one few should buy in their first year. A round, flat Amazonian cichlid of about 15 cm that moves with an almost solemn calm and, in captive-bred forms, wears impossible colours: turquoise, red, checkerboard.
Its difficult reputation does not come from temperament, which is calm, but from the water: it needs high, constant warmth, soft water and above all very clean water. Discus suffer from nitrate levels other fish never notice, which means large, frequent water changes.
If you are willing to do that, it is a fish that recognises its keeper, eats from the hand and forms a group with a visible hierarchy. If not, it is an expensive way to learn why it died.
Behavior
Peaceful, but gregarious and hierarchical. It is kept in a group of at least five or six: in a pair or trio, the dominant fish harasses the weakest until it stops eating. In a group the pressure is spread out.
It is shy and startles at sudden movement outside the glass and at nervous tank mates. A stressed discus darkens and stops eating, which is the first sign something is wrong.
It lives well with very few fish, because almost none tolerate 28-30 °C continuously. The safest companion is the sterbai cory; other common tetras and bottom dwellers are at the edge of their range.
Avoid housing it with angelfish, which compete for food and pass on disease; barbs and any fast or nipping fish; and almost all community fish, which cannot take its temperature.
Habitat
Symphysodon aequifasciatus lives in the Amazon basin, in lakes and floodplain channels of soft, acidic, warm water, among roots and fallen branches along the banks. In the rainy season it spreads into the flooded forest.
Its taxonomy is still debated: the trade uses names based on colour and origin, and shop discus are almost always captive strains that have been in aquariums for decades. Those strains tolerate slightly harder water than wild fish, but they need the heat just the same.
For the aquarium that means wood, roots, moderate light and an open bottom that is easy to siphon: cleanliness matters more than décor.
Habitats
Fish sharing this habitat
These fish appear in one or more habitats linked to this profile. It doesn't mean they are directly compatible in an aquarium.
Details
🌊 Water parameters
🐠 Minimum tank size
Breeding
It forms pairs and spawns on a vertical surface: a ceramic cone, a broad leaf or the glass itself. Both parents tend the eggs and then do something almost unique among fish: they feed the fry on a mucus secreted by their skin. The fry cling to the parents' flanks and feed from them for the first weeks.
Breeding at home requires water even softer and more acidic than for keeping, and young pairs often eat their first spawns. That is normal; they usually get it right by the third or fourth.
Diet
Omnivorous with a carnivorous lean, and a slow eater, which is a problem in a shared tank.
- Staple: quality granules made for discus.
- Supplement: frozen mosquito larvae, brine shrimp and mysis.
- Careful with: beef heart, widely used by breeders; it fouls the water and is best left to those who know how to handle it.
It eats several times a day in small portions, and whatever it leaves must be removed quickly: leftovers on the bottom are exactly what drives up the nitrate it is so sensitive to.
What about your tank?
Enter your tank's values to see only the compatible species that fit them. Litres apply to fish.
Compatible fish
General guidance based on water parameters, behaviour and known exceptions; always review the individual animals' and aquarium's specific needs.
They share water: pH 6–7 and 27–28 °C.
They share water: pH 6–7 and 27 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 6–7 and 27 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 6–7 and 27 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 6–7 and 27–28 °C.
They share water: pH 5.5–7 and 27–28 °C.
They share water: pH 7 and 27–28 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 6.5–7 and 27–28 °C.
They share water: pH 6–7 and 27–28 °C.
They share water: pH 6–7 and 27–28 °C.
They share water: pH 6–7 and 27–28 °C.
They share water: pH 6–7 and 27–28 °C.
They share water: pH 6–7 and 27 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7 and 27 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 5.5–7 and 27–30 °C.
They share water: pH 5–6.5 and 27–28 °C.
They share water: pH 5.5–7 and 27–28 °C.
They share water: pH 5.5–7 and 27–28 °C.
They share water: pH 5.5–7 and 27 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 5.5–7 and 27 °C. They only meet at the very edge, so the tank has to hold that value.
Compatible invertebrates
General guidance based on water parameters, behaviour and known exceptions; always review the individual animals' and aquarium's specific needs.
They share water: pH 7 and 27–28 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 6.5–7 and 27 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7 and 27–28 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7 and 27–28 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 6.5–7 and 27 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7 and 27–28 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7 and 27–28 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 6.5–7 and 27–28 °C.
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They share water: pH 7 and 27–28 °C. They only meet at the very edge, so the tank has to hold that value.
Sources
- FishBaseFroese, R. and D. Pauly. Editors. 2026. FishBase. World Wide Web electronic publication.
- Seriously FishSeriously Fish. Symphysodon aequifasciatus. Ficha de especie; consultada 2026-08.
Seriously Fish gives no water parameters. FishBase reaches pH 8 and dH 12; the profile stays in the soft, acidic part of that range.
Plan your next aquarium
Is this fish right for you? Plan a suitable aquarium before setting it up.