Often known as the “king of aquarium fish,” discus earn their title through their gorgeous colors, patterns, and variations. Particular strains of them are highly sought after, and some can easily reach a price of hundreds of dollars for just one.

Even though this species of fish is so beautiful, they are not as commonly found in the hobby as other fish. This is likely because there is another connotation about discus being one of the most difficult freshwater fish to keep. While discus fish care may require more attention than other aquarium fish, the thought of owning discus should not intimidate experienced aquarists. As long as they are kept in ideal conditions with routine maintenance, there should be no problems.

Tank Size

While it’s possible for discus to reach a length of 9 inches, this is only if they’re kept for a long time in the best conditions possible. Most discus in the common aquarium max out at 4.5-6 inches.

Based on this size range, the minimum tank size would be a 55 gallon tank, but the bigger the better for these guys. 3-5 discus should be doable in a 55gal aquarium as long as water changes are kept up with. A general rule you can follow is one discus per 10 gallons. Since these fish are tall, do not keep them in shallow tanks. The UNS 90U, 120P, and 120U are all high quality aquariums that would be great for discus!

Filtration

Good filtration is necessary to keep the aquarium clean and make sure the water is chemically clean. Discus fish will not do well in tanks where nitrogen levels are spiking or unstable. Make sure the aquarium is fully cycled before adding them in.

• Learn more about the importance of and how to cycle your fish tank HERE.

Since these fish are usually kept in larger tanks, stronger and bigger filtration might prove to be better. Sump filters are great for large aquariums, but can be hard to set up. A great option to consider is a canister filter like the UNS Delta 120 or Delta 90. Canister filters hold a lot of media for necessary beneficial bacteria and usually provide a current that is strong enough to pull the debris from the tank into the filter. Just make sure to clean the filter regularly!

Water Parameters for a Discus Tank

Temperature

Water quality and parameters are important when considering keeping discus. Unlike most other tropical fish that prefer water temperatures of 78F or lower, discus like it warmer. Depending on how you’re keeping your discus, different temperatures may be more suitable for your setup.

• For keeping discus in general: 84F-86F
• For raising young or growing juveniles: 86F-88F
  The increased temperature will speed up their metabolism, allowing for more feedings and faster growth.
• For breeding or keeping in a planted tank: 82F
  The lower temperature mimics the natural environment of the Amazon’s rainy season, stimulating them to breed.

Keep in mind that most aquarium plants don’t do well in hot temperatures. You must consider hardy plants such as bucephalandra, anubias, and java fern, and give them time to adapt to the warmer temperatures.

Note: When maintaining a planted aquarium with high temperatures, aeration is very important. The warmer the water, the less ability it has to hold oxygen, so make sure there’s enough oxygen for the fish by installing an air pump if necessary.

pH & Hardness

Discus prefer soft, acidic water. Ideally, a pH of 7 or below and a gH of 1-3 is what many strive for in a discus aquarium. While this is probably best for them, it’s not impossible to keep healthy discus in higher pH/hardness levels. They’ve been bred in different water conditions around the world and are capable of adapting to other ones. In general, a pH of 7.5 or less and a soft to medium hardness level will work just fine.

Why a Planted Tank is the Best Idea

After going through all the preferences for a discus tank setup, the conclusion is that planted aquariums could be considered the ideal setup for discus because they help achieve the ideal conditions for keeping discus.

• Arguably, the best filtration for aquariums are aquatic plants! Plants will absorb ammonia and nitrates right out of the water when they grow, chemically cleaning the water. More plants and carefully injecting CO2 to help them grow will filter the water even more.
• Aquatic plant substrates like UNS Controsoil are not only designed to help plants thrive, but they also stabilize and buffer the pH to optimal levels for most tropical fish. Planted tanks that use these nutrient-rich substrates are more ideal for discus than bare bottomed tanks.
• Driftwood, a common type of hardscape to use in an aquascape, also lowers the pH and hardness of the water.
• The greens of the plants will contrast the colors of the discus, resulting in a beautiful pop of color.

Maintenance is Important!

Heads up: you cannot slack on tank maintenance when it comes to discus. Even if you have a planted tank, a weekly water change of at least 20% should be performed. Approximately 40% or more in a non-planted aquarium. It really depends on how many fish, the bioload, and the size of the tank. Make sure to siphon out as much detritus as you can during each session.

• Click here to learn more about the importance of water changes in your fish tank.

Diet

Discus can be picky eaters, so try to feed a variety of foods like flakes, pellets, and frozen/live foods. When it comes to how often you should feed your discus, feed them no more than 3% of their body weight. On average, adult discus (1+ years) should be fed 2-3 times per day. When feeding, make sure you have clean hands free of any lotion or hand sanitizer. 

Changing up the types of food you feed will prevent them from sticking to only ever going after one food. If you receive new picky discus, but you want to feed them flakes instead of bloodworms, slowly introduce the new food (ex. flakes) while also feeding their original food (ex. bloodworms).

Tank Mates

Friendly/non-aggressive community fish that are big enough to not be seen as snacks should do well with discus. Freshwater shrimp can be too stressed in an environment with discus, but it depends on the scape and whether they have ample area to hide and explore without being bothered by the discus.

Keep in mind, any fauna you add to the tank need to be able to handle the hot temperatures that discus like to be kept in. They should also be fast enough to avoid getting eaten by discus, but not so fast that they outcompete them for food, as discus can be slow when it comes to eating. Great examples of tankmates are cardinal tetras, rummynose tetras, sterbai corys, small plecos, and rams!

 
Happy Black Rams in Buce Plant's Discus tank

Hopefully this info help guide those interested in keeping discus. If you’re already a passionate aquarist that regularly stays on top of their maintenance, then these fish shouldn’t be any different!

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