The best equipment for a discus aquarium

Which aquarium, which filter and how much heating do you need for discus? A practical overview of the equipment that makes the difference.

Blue discus in an aquascaped aquarium with driftwood
Photo: Rjcastillo, CC BY-SA 4.0, via Wikimedia Commons

Discus are more demanding about their environment than most aquarium fish: warm, clean and stable water. The right equipment makes maintenance a lot easier.

The aquarium

Discus grow large and tall. Count on an aquarium of at least 120 cm long and 50 cm high, with around 300 litres for a group of five to six adult fish. More volume means more stable water parameters and less stress.

Filtration

  • Choose a powerful biological filter: an external canister filter or a sump under the tank.
  • Discus don’t like strong currents. Aim the outflow at the glass or use a spray bar.
  • A turnover of three to five times the tank volume per hour is a good starting point.
  • Clean the filter regularly in aquarium water, but never all of it at once.

Heating

Discus need 28 to 30 °C. Preferably split the wattage over two heaters: if one fails, the tank doesn’t cool down straight away, and if one sticks on, it overheats less quickly. A separate thermometer checks that everything is right.

Water

Many discus keepers use a reverse osmosis unit to make soft water, and a separate heated storage barrel to prepare replacement water. An automatic water change system makes small daily changes easy.

Lighting

Discus are shy under bright light. Choose moderate LED lighting, set a timer for eight to ten hours, and use floating plants to create shade. In a planted tank the light must still be strong enough for the plants: find the happy medium.

Substrate and decoration

Breeders often keep discus in bare tanks because they are easy to keep clean. In a display aquarium, a thin layer of fine sand is a good choice. Driftwood and large plants provide calm and hiding places; avoid sharp rocks.

Useful extras

  • UV-C steriliser: kills free-floating bacteria and parasites in the water.
  • Aeration: warm water holds less oxygen; an air stone helps, especially at night.
  • Conductivity meter (EC/TDS): handy for mixing RO and tap water.
  • Test kits for pH, KH, GH, nitrite and nitrate.

Checklist

  • Aquarium of at least 120 × 50 cm (length × height)
  • Biological canister filter or sump with gentle outflow
  • Two heaters plus a thermometer
  • Reverse osmosis unit and a storage barrel
  • Dimmable LED lighting with a timer
  • Test kits and a conductivity meter