Discus Care Sheet

Discussing Discus Dynamics

There is no denying that discus are viewed as a show stopper, even among individuals who don’t own aquariums. We have our 150 gallon (568 L) discus aquarium positioned at the entrance of our home. Everyone we greet at the door can’t help but stare transfixed by the aquarium for a few moments. While these aquatic beauties are eye catching, they do entail their own unique requirements. In the past, we have discussed the equipment running our system and the maintenance we conduct on the tank. However, this article will focus on describing discus. We will be highlighting their physical attributes, housing requirements & our own personal anecdotal observation of behavioral tendencies.

Physical Attributes

Size: Fully grown discus can reach a size of 7 inches (18 cm) or more

Life Span: 7 to 8 years. Though there are “fish tales” of discus living for 10+ years. Poor husbandry will dramatically shorten their life expectancy
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Appearance: Discus should have a round shape from which it derives its name. When viewing head on, their forehead should not appear pinched nor should their abdomen region. Fins should not be clamped, but outstretched. Discus fish which are dark in coloring are typically stressed. ​

Big Blue is roughly 6.5 inches (17 cm) exhibiting a round body & broad forehead

Growth Rate: Young discus grow very quickly within their first year. In order to help a discus achieve its optimal size, multiple daily feedings and pristine water conditions (be ready for daily water changes) are required. If it is your first time keeping discus, we encourage individuals to purchase fish that are closer to their adult size. It can be extremely demanding to grow out discus. It is typically advised that growing discus occupy their own bare bottom tank to assist with the frequent feedings and water changes. Failing to keep growing discus within these conditions can resulted in stunted fish. Stunted discus are easily identified by their oval or “football” shaped appearance and unusually large eyes. Even within our own discus tank, we have a few stunted members. Little Blue is 4 inches (10 cm). We fondly refer to Little Blue as “Football Head” (Easter Egg for you Nicktoons Kids out there). While a few of our fish have become stunted, we have also experienced success with growing out young discus. When we purchased Little Red he was smaller than a quarter. Now he is one of the larger fish in our tank at a little over 6 inches (15 cm). Regardless of their size, we love every member of our discus brood & find endless enjoyment from each of their unique personalities. Which brings us to our next topic…

Shape comparison of Little Red vs. our stunted Little Blue

Growth of Little Red over a year

Behavioral Characteristics

Cichlid Fish: Discus belong to the family Cichlidae, commonly referred to as cichlids. Just like breed knowledge is important when selecting a puppy, understanding the fish family is crucial for aquatic success. As with many cichlids, discus exhibit intelligent behavior, intricate courtship practices, rearing responsibilities & aggressive tendencies.

Group Mentality: School is in session for these fish! Discus are shoaling fish, meaning they obtain security and socialize among a group of other discus. For this reason it is strongly encouraged to keep discus in a group of 6 or more. Additionally, larger groups will help to alleviate aggression among individuals. Remember discus are cichlid fish and can at times show aggression towards their own kind. Maintaining a larger group of discus permits members to distribute a slight peck here or there without one member being persistently picked upon. Most of the aggression witnessed within our tank was due to establishing a pecking order. Discus kept in small groups frequently witness one member constantly bullied by the more dominant discus.

Discus Mating: It has been reported that discus are monogamous, mating for life. I’m sorry to burst the romantic bubble, but this is a misnomer. Discus do pair up when it comes time for mating. The will remain a mated pair working cooperatively in protecting eggs and raising young. Following the conclusion of spawning and rearing young, discus may remain a mated pair or move on to “greener pastures”. Much of the discus drama in our tank has circled around mated pairs, but that is a story for another day.

Bee & Big Red are one of the only mated discus that have remained a consistent pair in our tank

Aquarium Requirements

Minimum Tank Size: 55 gallons & that is the bare minimum. However, this is one of those cases where bigger is better. Let’s face it, you like big fish that’s why you are reading about discus and not minnows. So get your big fish a big home. Preferably, we recommend starting within the 65 to 75 gallon range, but I would buy as much tank as your budget and interior space allows. Remember discus do best in groups of 6 or more and you typically want to allocate 10 gallons of space per fish.

Temperature Range: 82 - 86F (28 - 30 C)

Water Requirements: I’m going to be brutally honest on this one. If you loathe water changes, discus are probably not the right fish for you. This is not a fish where you can get away with skipping water changes. On our discus tank, we conduct at minimum a water change of 70% once a week. Water changes are the primary method to insure good water chemistry. We also have a crazy amount of filtration on our aquarium. Check out our tank specs for more information on the equipment we use. Water cleanliness is key. Each month we rotate cleaning one of our canister filters in order to remove built up debris and waste from filter media. Mechanical & chemical methods of filtration will also assist you with your endeavor of maintaining desired water parameters.

Some sources will tell you that the ideal pH for discus is 6 and to never allow levels to rise above 7. However, we have found that consistency is key. The average pH of our tank runs around 8. The most detrimental occurrence for any fish, not just exclusively discus, is to experience pH swings. Rather than constantly fighting to keep the pH levels lower in our tank, we choose to keep the levels stable and have witnessed no ill effects towards our fish. Many have reported keeping healthy, happy discus for years within elevated pH levels. ​
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Tankmates: Many discus hobbyists choose to keep exclusively discus aquariums. However, many fish are compatible with discus if you are seeking a little diversity within your aquarium. Some things to keep in mind when selecting tankmates:

• Select fish which are tolerant of the higher temperatures required for discus
• Avoid small fish which could quickly become discus dinner
• Steer clear of "nippy" fish
• Fast-moving fish can easily startle discus

Fish frequently paired with discus include: Rummy-Nose, Cardinals & Lemon tetra. Personally, we choose to include cardinals and rummy-nose tetra within our aquarium and greatly enjoy the schooling behavior of these fish. Rams (German Blue, Electric Blue, Golden & Bolivian Rams) also make suitable tankmates. In regards to clean-up crew many rely upon bristlenose catfish (Ancistrus), amano shrimp (could potentially become lunch), schools of cory and otocinclus catfish (otos). We’ve attempted to keep otos within our discus tank before; however, they rarely made it past the 6 month mark. They would make it through their quarantine period safely, but never last more than a few months within the discus tank. We suspect that the higher temperatures might affect their lifespan. It should also be noted that some have reported otos attaching to discus to eat away at their slime coat. Though we never witnessed this aggressive behavior within our tank; should you choose to add otos, observe the fish to insure that there is no threat towards your discus.

We also keep angelfish within our discus tank. Angelfish are also categorized in the cichlid fish family. Within discus keeping, there is a great debate if angelfish can be kept safely with discus. Many have reported that angelfish harass and stress discus. Additionally, angelfish can carry diseases which could be passed along to discus. To date, we have never witnessed our angelfish upset or harm the discus in any way. The discus at times have quarreled amongst each other when establishing a pecking order; however, the angelfish have never become involved. They typically swim with the rest of the discus group. We enjoy the variety the angelfish bring to the aquarium. Additionally, we find that angelfish do not startle as easily which appears to put the discus at ease. During water changes, the discus & angelfish typically hide from view. Once the water change is complete, the angelfish are the first to reemerge followed shortly by the discus. 

Angelfish front and center following a water change

We introduced the angelfish into our discus tank early into our stocking process. At the time, the 150 gallon tank housed a total of 5 discus. The two angelfish had gone through a quarantine period where they were carefully observed and treated for any potential pathogens which could be passed along to the discus. When the angelfish were added, the discus were significantly larger than the angelfish and had been housed within the aquarium for 2 months preceding the angelfish introduction. The angelfish’s diminutive size, coming into an established territory and being outnumbered have potentially aided our peaceful arrangement. Additionally, the angelfish are not a mated pair so there is no hostility which could potentially arise during angelfish spawning. With all that said, it should be noted that our aquarium arrangement is only one data point. Many have reported experiencing issues surrounding housing discus and angelfish together. Should you decided to attempt the endeavor, please follow strict quarantine procedures and observe all fish during introduction. For all fish introduced with discus, not exclusively angelfish, be prepared to remove & re-home fish that present a danger to each other.

Feeding Requirements

Food Selection: As with all fish, a varied diet generates healthy fish. However, for discus our staple meal is beefheart. Beefheart is extremely high in protein which provides growing discus with the nutrients they need. We generate our own beefheart mixture roughly every three months and freeze the prepared meals. In the future, we plan to post information surrounding the exact ingredients and steps we utilize for our beefheart mixture. Other meals to consider for a discus diet include frozen bloodworms (we use Hikari) & dried pellets (we use Colbalt Discus Flakes & TetraColor Tropical Granules).

Prepared Beefheart Mixture

Feeding Frequency: Our adult discus receive meals twice daily. However if you are growing young discus, it is much better to feed multiple smaller meals throughout the day. Remember underfed discus can become stunted.

Anecdotal Observations

Moonlights: When we initially set up our discus aquarium, we did not have moonlights above the aquarium. We found at night the discus became extremely jumpy. The slightest shadow would cause splashing and mad darting across the aquarium. To rectify the issue, we placed a strip of moonlight across the top. Since the installation of the moonlights, we have not observed the discus become startled with outside tank movements.

Moonlights over our aquarium. We run Neptune Apex moonlights; however, many aquarium lights come with moonlight settings.

​Skittish Nature: Some within the hobby have advised against placing a discus aquarium within a high traffic area since they can be skittish by nature. We have our aquarium located within the entryway of our home. We frequent this area daily as we come and go. This location, as you can imagine, also receives a lot of activity as we welcome guests into our home. We have not witnessed any ill effects towards the fish within this location. Many are enamored with the aquarium when they first arrive and instantly approach the glass for a closer look. All of our fish eagerly swim up to meet the guest (in hopes of meal I presume). However, we do provide coverage areas in the corners of the tank with decorative plants so the discus have a place to withdraw should they feel the need to hide in order to feel secure. Make sure to include hiding areas within your aquarium.

​Aquarium Coverage: Put a lid on it! Seriously. Discus can become startled and when they do it is apparent through mad dashes and the occasional splash of water. Discus could easily clear the water surface and jump from the aquarium. It does not happen frequently, but I can recall one occasion (accidental slamming of a back door) which caused one of our fish to jump. Had it not been for our lid, we might have had a fish outta water situation. Please keep a lid securely over your aquarium. Even rimless tanks have netted cover options which detract little from the aquarium aesthetic but provide security for your fish. In the coming weeks we will be installing one of these options on our 12 gallon rimless saltwater tank.

In Summary

Discus are a joy to watch and own. Nothing beats a stressful day at work better than just watching these ethereal creatures seamlessly float through the water. Overtime, you get to observe their unique personalities and discover that they are very different from many other freshwater fish. Their presence does require additional maintenance not necessary for other freshwater aquariums. If you are considering keeping discus, please take the time to read through our maintenance schedule in order to help you determine if you have the time necessary to dedicate to these fish. While demanding, these creatures are more than worth the effort.  Additionally, for those considering discus: I would strongly recommend visiting Simply Discus. The site has a plethora of information dedicated strictly to discus keeping for both the beginner and advanced aquarist. They also have a wonderful community forum who are happy to offer advise and their own observations on discus fish. We would not have experienced as much success with our aquarium if it was not for this resource.


​Keep Krill’in!