For discus fish, there are 2 considerations in tanks: depth and volume of the tank. Due to their size and swimming habits, a minimum of 18″ is needed for tank depth, the deeper the better. As for volume, a good rule of thumb is that each adult discus will need 10 gallons of water. Larger ones will also give more stable water conditions, and with other considerations in mind, the minimum size for a discus display tank should be no less than 55 gallons. that are more efficient as they maximize surface area. Surface area is the most important factor when purchasing a tank. Why? Because it is only on the surface of the tank that gas exchange occurs. (Oxygen in, oxygen out). carbon dioxide)., and its biological filter works as required, up to twenty 3-inch size young fish, or 6 or 8 fully adult discus can comfortably inhabit the tank.A filter can be added external to large tanks to increase basic needs for aeration and biological filtration. .
Keep in mind that when young discus fish are small, they grow rapidly and become quite large in a short period of time if fed well and water quality is maintained. If your tank is too small, they will not be happy and you will quickly stunt their growth. Juvenile discus should not be kept in tanks that are too large. Being a social fish, Discus tends to get very skittish in large tanks. At our hatchery, we put 6 discus up to 1.5″ in a 29 gallon tank. They will move to larger tanks when they get to 2.5″ and show possible signs of “mating”. Always try to buy the largest tank you can afford for discus fish.
If Discus is considered for later breeding, tanks can be reduced to twenty gallons per pair. At our hatchery, 29 gallon rectangular glass tanks are used for each breeding pair.
To begin the process, a bare bottom tank with 2 ½ gallons of water per inch of fish, a pair of sponge filters, and a cartridge filter with activated carbon are used. This is kept at 6.6 – 6.8 PH, and the temperature is set at 82 to 84 degrees F. We do 50% water changes weekly, with some breeders going as high as 95%. Optimal results would be achieved with a daily 15% water change. Because the discs produce slime on their body and are shed regularly, it coats the inner surface of the tank and promotes bacterial growth. A safe bet is to clean all disc tanks every week. There are commercial sponges and brushes available to do this task.
Because discus are large fish, they require clean water and proper filtration. The tank must be “cycled” and tested for nitrates/nitrites before placing Discus in the tank. Our policy is to use fish such as some of the more common cichlids to “cycle” the tank. A good rule of thumb here is to wait at least 4 weeks before attempting to place Discus with the “cyclist” fish. If you are an active member of the aquarist community, you may be loaned some “cycler fish” by a friend to start your project, and the “cyclers” can be returned to their owner at the end of the cycle.
Discus prefer soft water, due to constant rain and runoff in their natural habitat. However, we are more concerned with cleanliness. It is much better to have a high quality of tank hygiene than to have optimal water conditions, although we strive for both. Discus will adapt to most conditions, including PH up to 7.8 and microsiemens hardness of 350ppm, but cannot survive in constantly changing or dirty water conditions.