Discus are colorful, graceful and charismatic tank inhabitants. Discus are considered to require a higher level of care than other aquarium fish. Their basic requirements are a larger aquarium (3ft+ is recommended) and stable, clean water. For this reason alone they are not recommended for the beginner aquarist. Discus can be housed with many any other fish as long as they require the same water conditions. They are not compatible with larger aggressive fish such as oscar's or smaller fin nipping varieties.
Discus do best with smaller tetra’s such as neon tetras, cardinal tetras, ember tetras, harlequin tetras and rummynose tetras. Tetras are usually the most common compliment to discus as they contrast the size and add movement to the aquarium.
The optimum aquarium temperature for Discus is around 82°F - 88°F (28°C-31°C). Note that higher temperatures such as these lower dissolved oxygen and limit the number of fish housed in the aquarium. When choosing other fish to go in the aquarium try and fit them in this temperature bound.
pH ~6.5 | Hardness 4.0
Keep your pH between about 6 and 7. The ideal pH for discus is around 6.5. If your pH is over 7 or below 6 it may begin to cause discus stress. Tank bred Discus species have been known to thrive in pH as high as 7.8 as long as there is little/no fluctuation.
Relative water hardness should be 1dH - 8dH. This will replicate relatively soft conditions similar to the amazon. Some tank bred variety's are known to withstand higher dH. Water hardness can be softened with the addition of a piece of diftwood to the aquarium water.
Max Size ~6.5"
Both males and females can grow to around 6.5" (16.5cm) over the course of two years.
Discus are highly susceptible to even very low levels of nitrite in the aquarium.
Discus are very sensitive to any ammonia levels. There will be noticeable loss of color and heavy breathing if ammonia is present. An immediate water change is required.
Nitrates should be as close to 0ppm as possible. Any reading under 20ppm is suitable for keeping Discus, elevated levels can be reduced by adding aquatic plants and removing any decaying matter.
Water Changes >50%
Discus require the aquarium water should be changed at least 50% each week to reduce nitrates and replenish minerals. Discus are messy feeders and big contributors to nitrates in the aquarium. Be sure to dechlorinate the water before it is changed.
Discus are usually combined with planted aquariums. Planted tanks with CO2 injection will usually exhibit a lower pH of around 6.8 which is perfect for Discus. Discus, originally a species from the amazon will feel right at home with a mixture of long stem plants and lower foreground plants. Driftwood is also an excellent compliment that will help these fish feel at home. It will add to the beauty of the aquarium and it will also soften the water and lower the pH to a suitable environment.
Alternatively, Discus can be housed in a bare bottomed tank. Some hobbyists believe this is the best way to care for discus even though it is not as aesthetically pleasing. Having no substrate allows the tank to be easily cleaned from faeces and rotting debris. This is a sure way to keep the water quality stable and immaculate. When breeding Discus it is highly recommended to put them into a bare bottomed tank. This has a number of advantages including a safe environment for the young and easy aquarium maintenance.