The discus fish is one of the most sought-after fish in the pet trade. It’s shoaling habits, flattened profile, and magnificent coloration make it irresistible.
These fish have a reputation for being finicky and hard to care for. While they have certain requirements, almost any experienced keeper can tend these fish.
We wouldn’t recommend getting these fish if you are a beginner. However, they thrive if you meet their needs.
In this article, we’ll break down the care requirements so even a novice can follow them.
We’ll take a look at the following:
- Where discus fish come from, and their natural habitat
- Which tank size you’ll need
- How to go about discus aquarium setup
- Choosing discus tankmates
- Discus breeding setups
- And more!
Let’s get into it.
Discus Fish in a Nutshell
Origin: South America, mainly the Amazon River Basin and Rio Negro
Natural Habitat: Slow-moving, vegetation-rich waters of the Amazon River Basin
Size: 4.8 to 6 inches
Temperament: Calm, docile, social. Not prone to bullying, but may get picked on.
Tank Size: At least 55-gallon per pair, and ten gallons more for each additional fish.
Water Parameters: Slightly acidic (pH 6.0), soft, 82-86°F
Water Changes: 25% to 30% weekly, with a 50% change once a month
Lifespan: 10-15 years
Discus Fish: Background and Origin
Dr. Johan Heckel first discovered the discus, in 1840. Today, scientists acknowledge three species:
- Symphysodon aequifasciata
- S. discus
- S. tarzoo
These fish belong to the family Cichlidae, which includes diverse species like:
- Malawi Cichlids
- South American Dwarf Cichlids
- Lake Tanganyika Peacocks
Despite their many differences, all Cichlids share one characteristic: parental care. In the case of discus fish, both parents guard the eggs and young.
The discus gets its name from a superficial resemblance to the discus used in sport. It’s round, and flattened from both sides, just like the traditional throwing disc.
Discus fish come in every color of the rainbow. Not long after describing the discus, scientists discovered regional color differences.
Appearance and Color
For instance, the upper Amazon boasts a green form, while the lower reaches has a brown form. In other areas, the fish may be blue or red.
Some keepers claim that discus with red eyes are superior to other types. Eye color is genetic, and not a matter of superiority. In every other way, fish with red eyes are the same as those with black or brown eyes.
It’s worth noting that Heckel’s Discus, Symphysodon discus, is a separate species from the fish we generally see in the pet trade.
Heckel’s discus has a unique appearance, sporting a broad band through the center of its body. It has a band at the base of its tail, and one through its eye. It’s usually brownish-green with reddish-brown, wavy patterning.
You may see pure specimens of this species in the pet trade, but you’re more likely to encounter hybrids. Enterprising breeders crossed discus species to create a diversity of patterns and colors.
If your discus variety has a broad central band, it probably contains some blood from the Heckel’s discus.
Some of the discus colors and varieties you’re likely to encounter include:
- Blue Diamond – A spectacular dark blue variety with green shading on its flanks. It entirely, or nearly completely, lacks the natural wavy patterning. Red eye coloration is a significant feature in this type of discus.
- Cobalt Blue – A much lighter blue than the blue diamond, the cobalt blue generally has more markings. Breeders prefer them to be as free of darker markings as possible. As with the diamond, cobalts often have red eyes.
- Snakeskin – The snakeskin may come in a variety of colors. It’s named after the wavy horizontal lines that covers its entire body. People claim that it resembles the scaly pattern of many snakes.
- Pigeon blood – The pigeon blood maintains some faded horizontal banding. This variety has a brilliant orange-red coloration.
- Brown – The standard brown coloration remains alive and well in the aquarium trade. Breeders have been very strict about not allowing it to fade into obscurity. They claim that it produces more fry than other colors.
A brief search will turn up many other varieties of discus fish, but covering them all in detail is a topic unto itself.
Temperament and Compatibility
Discus are some of the most peaceful fish that you’re likely to encounter.
You’re unlikely to have any problems with them picking on other fish in the aquarium, unless they spawn. Breeding pairs chase other fish away from their breeding area. This can lead to injured tank mates, and high stress levels.
Pro tip: Discus fish are social, and need a shoal to be happy. Unless you’re breeding a single pair, we recommend having at least six to eight discus.
Due to their peaceful nature and long fins, discus fish are often the victim of bullying.
Discus Tank Mates
When keeping these fish in a community setup, it’s essential to pick your discus’ tank mates with care.
The basic criteria include:
- No tank mates smaller than two inches, because the discus might eat them.
- They’re susceptible to fin nipping, so no tank mates with nippy tendencies.
- Discus have calm personalities and boisterous tank mates can be a source of stress.
- Discus are mid-level fish, so consider adding some bottom and surface dwellers.
- They need soft, acidic conditions. Their companions should reflect these needs.
Here are some of our top picks:
Surface Dwellers Discus Tank Mates
- Common or Silver Hatchetfish – The largest of the hatchetfish. They’re ideal companions because they’re too large to swallow, and prefer similar conditions.
- Gouramis – We’d recommend pearl or honey gouramis, since they’re quite laid-back and don’t usually have nippish tendencies.
Mid-Level Fish Discus Tank Mates
- Larger Tetras – Larger tetras get along quite well with discus, and are too large to swallow. They also have the same water requirements. We’d suggest species like:
- Cardinal Tetra
- Rummynose Tetra
- Lemon Tetra
- Black Neon Tetra
- Black Widow Tetra
Pro tip: Avoid keeping standard neon tetras with your discus in any but the largest aquariums. Due to their small size, they tend to become a snack!
- Scissortail Rasboras – A peaceful fish with an adequate size that helps keep your discus calm.
- Angelfish – Angelfish can make good companions for discus, since they have similar habits. If keeping them together, include plenty of dither fish to keep territoriality minimal.
Bottom Dwellers Discus Tank Mates
- Bristlenose Plecostomus – The bristlenose pleco remains a bit smaller than the discus, and has a wonderful personality.
Pro tip: Never opt for any of the larger plecos, or the Siamese algae eaters. These fish can suck the mucus layer from the discus’ skin, and lead to illness.
- Larger Corydoras – Any of the larger corys will make great discus tank mates. They’re extremely peaceful, and help keep the tank clean.
Buying and Introducing New Discus Fish
Some people believe that if you buy new discus, you have to buy them all from the same place. The official reasoning is either:
- Discus purchased from different sources will refuse to blend into a single cohesive shoal
- Different breeders use different water parameters, and fish from two different places won’t adapt equally well
On the first count, if no-one blended fish from different breeders, the genetics of captive discus would quickly deteriorate. You need new blood from different sources, especially if you plan on breeding your fish.
However, discus from different sources may sometimes struggle to blend into a cohesive shoal. To avoid this, we suggest buying young fish. After the quarantine period, add the new fish from both sources to the main aquarium at the same time.
By preventing either group of fish from establishing territories before you add the others, you essentially force them to group together for safety. They’ll quickly blend into a single shoal under these conditions.
On the second count, most fishkeepers shop around, and many order fish from other parts of the country. If you quarantine correctly, both groups of fish will adapt to your water conditions at their own pace.
Finally, no matter how carefully you quarantine, one group of fish may get sick when exposed to another.
Why is that? Well, once a group of fish gets sick and recovers, it carries antibodies for that disease. Those fish are immune to the strain they had, but may still transmit it to other fish.
When you expose one group of fish to another, the fish that don’t have immunity can get sick.
For some reason, this phenomenon gets more attention in discus. Hobbyists sometimes even refer to it as a ‘Discus plague’. If you’re concerned that this might happen, then you may wish to stick to buying fish from a single supplier.
Whenever you buy new fish, whether they be discus or guppies, keep them in quarantine for two weeks. This allows your new fish to adapt to your water parameters. It also lets you treat any signs of disease in your new acquisitions.
If you buy several groups of fish from different suppliers, it’s best to have a separate quarantine tank for each supplier.
After two weeks, if the fish seem healthy, you can introduce them to the main tank. Remember to give your fish the benefit of a 20-minute float if there’s even a marginal difference between the water temperatures in the different tanks.
The 20-Minute Float
Whenever introducing fish from one aquarium or location to another, you need to equalize the temperatures so they don’t go into shock. You can do this by placing them in a bag with some of the water from their old aquarium.
Use an elastic band to seal the bag, then float it on top of their new tank for 20 minutes. After this time, the temperatures inside the bag and the aquarium will be the same. You can then use a net to remove the fish from the bag.
Never add the water from the bag, to help reduce the risk of spreading diseases and parasites from one tank to another.
Discus Fish Tank Setup
Let’s look at the main criteria when setting up your discus aquarium.
Discus are quite large, and require correspondingly large aquariums. For a single pair of discus, we’d recommend a 75-gallon tank.
This is partly because it’s easier to keep larger amounts of water clean. Smaller tanks equal smaller filters, and more regular water changes.
If you’re willing to put more work into cleaning, you could keep a pair of discus in a 55-gallon.
Working up from the starting size for one pair, you can add ten extra gallons per discus, as a rule of thumb. For instance, if you start with a 55-gallon for one pair, you can keep two pairs in a 75-gallon.
Considering that these are social, shoaling fish, we’d recommend starting with at least a 100-gallon aquarium.
Discus come from the Amazon River Basin, where the water is soft and slightly acidic due to the decay of fallen leaves.
To give your fish their best life, your discus tank should have similar conditions. If you live in an area with hard water, you can remove a large percentage of the water hardness by boiling it.
However, this is only partially effective, and it’s much better to run the water through a reverse osmosis filter, or to buy soft water.
In terms of pH, these fish prefer a measurement of six. You can accomplish this by adding peat moss to the substrate, or adjusting the pH chemically.
These fish are extremely sensitive to nitrite, nitrate, and ammonia levels. Aim to keep:
- Nitrates below 25 Mg/L (milligrams per liter).
- Nitrite levels below 0.75 PPM (parts per million)
- Ammonia levels under 20 PPM
You can buy test kits at any pet store or tropical fish supply store, to help you track the levels. The best way to keep the numbers in an acceptable range is to do regular partial water changes (25% weekly).
If your numbers are consistently high, do a 50% water change every two weeks for a month. Alternatively, do a once-off 75% water change, and see if the numbers stabilize.
These fish prefer a temperature range of 82-86°F or 24-29°C.
Discus fish like a soft substrate, and often sift through the substrate in pursuit of food. Many aquarists recommend bare-bottom tanks, but we don’t feel that’s necessary. As long as you siphon the substrate regularly, your fish will thrive and the water will remain clean.
Peat moss is a common substrate choice, since it helps keep the water slightly acidic. Sand is another excellent option considering the sifting habits of discus fish. We wouldn’t recommend larger substrates like gravel and pebbles, because these fish like to dig sometimes.
While lighting probably isn’t the most essential element of discus fish care, we’d recommend adding at least a full-spectrum globe. Most fish, including discus, do best when they have a daily lighting schedule.
If you give your fish a 12-hour on, 12-hour off, lighting schedule, they’ll be content. We’d recommend using a timer to switch the lights on and off automatically.
Lighting the aquarium also allows you to:
- Grow plants
- Adjust lighting times to simulate seasons and induce breeding
Filtration and Water Flow
As mentioned above, Discus fish are extremely sensitive to water quality. Unfortunately, they’re also extremely messy eaters!
Combined with the fact that discus like a high oxygen level, this means that you need a particularly efficient filter. However, it’s worth noting that discus don’t like strong water currents.
So, which filters are best? We wouldn’t recommend corner or platform filters, because they just don’t have the power you need to keep the water clean.
In our opinion, the best filtration system is a combination of an undergravel filter, and a canister filter. UG filters convert the entire substrate into a storage bank of healthy bacteria, helping to control the nitrate cycle.
Canister filters have both the mechanical power, and bacterial filtration, that discus tanks need. However, be sure to set up the filter outlet so that it stirs up the water surface without creating a strong current beneath. This will give you sufficient oxygen levels without discomfiting the fish.
Should You do a Planted Discus Tank?
Yes! If you can, your discus fish will love you for giving them a planted tank. As mentioned earlier, these fish come from the Amazon river basin. This area has many different aquatic plants, and discus feel most at home in a planted tank.
What Kinds of Plants Should You Use?
If you’re doing a planted discus aquarium, you need to use plants that have similar water requirements. Discus sometimes nibble at plants, so you also want something non-toxic.
We suggest the following plants for the substrate:
If you want some floating plants, consider:
- Water Sprite
These plants all share similar water requirements to the discus themselves, and can handle the appropriate temperature range.
Discus Fish Feeding
Feeding discus is easy as long as you know and understand their preferences.
Are Discus Picky Eaters?
Discus fish can be mildly picky, but mostly seem that way because of their relatively small mouths. It comes down to personality, and different fish have their own preferences. One may eat anything, while another eats a very small number of things.
How Often Should Discus Eat?
Adult discus should get as much food as they’ll finish in five minutes, twice a day. Younger fish should receive as much as they’ll finish in a few minutes, but three to five times a day.
What Is Discus Favorite Food?
As mentioned above, discus are highly individualistic. Each fish is likely to have a favorite food.
Discus in general are often fond of live foods like bloodworms, blackworms, brine shrimp, and mosquito larvae. A large part of their natural diet is algae, so they’re also quite fond of spirulina wafers.
What Vegetables Do Discus Eat?
Discus are open to eating a broad array of vegetables, including:
- Green beans
- Red lettuce
It’s best to give all of these a quick blanching by dipping them in hot water before offering them to your fish.
Is Spinach Good For Discus?
Yes, spinach is good for discus, though you should be careful not to feed it excessively. It’s high in nutrients like iron, and can become harmful if you feed it to your fish too often.
How Do You Make Discus Grow Bigger?
If you want your discus to grow into big, strong fish, then a well-balanced diet is essential. Preferably, you should feed them a balanced dietary flake for discus, as well as regular feedings of live foods and vegetables.
If you feed your fish only commercial flake or pellets, it’s like a human trying to survive on nutritional shakes. Technically, it contains everything you need. But, it’s a tad boring and you’re unlikely to thrive on such a diet.
Try to provide live foods every other day at least if you’re aiming for fast, intensive growth.
Discus fish have one of the most diverse price ranges of all tropical fish. The plainest, most basic varieties may cost as little as $30.
Pedigree fish of a specific variety can cost significantly more, and some breeders sell their pairs for as much as $1,000.
The main reasoning behind this price difference lies in reputation and rarity. Certain breeders have a reputation for breeding high-quality fish and trade in that prestige to charge high prices. You’ll pay less if you buy from amateur breeders than from seasoned professionals.
Also, not every variety of Discus is equally common. If you buy a “mudblood” fish, which is a cross between more than one variety, it costs less. If you wish to delve into specific types or varieties, you’ll have to pay for the privilege. The rarer the variety is, the more it will cost you.
The discus is highly comparable to koi fish or goldfish, where price is concerned. You can walk into any pet store and buy a goldfish for as little as a dollar. A basic koi fish, which belongs to the same species, costs significantly more.
Specific rare koi varieties can cost tens of thousands of dollars, especially when bred by professional Japanese breeders.
Discus Breeding: What You Need to Know
Breeding discus might not be easy, but it’s also not as hard as people think. The main trick is to get the water conditions right. If you do, the discus ought to pair off by themselves.
When a pair of fish looks ready to breed, move them to a tank of their own with similar conditions. The temperature in the breeding tank should be around 82°F.
If you keep the water clean, boost the amount of live foods you feed, and try not to disturb the fish, they should breed without any further interference.
As with angelfish, the pair will clean a flat area, like a flowerpot or piece of slate, by nibbling at it. When the spawning site is clean, the female will lay up to 400 eggs, with the male fertilizing them as she does. If all goes according to plan, the eggs will hatch within three to four days.
Sadly, after the fish lay eggs is typically when most of the problems arise. Often, young discus parents will eat their first few batches of eggs. This may be the result of:
- Inexperience – Sometimes they just need some time to learn the ropes.
- Infertile eggs – If you see the fish picking out specific eggs among the batch, they may be infertile. Unfertilized eggs often turn white. In some cases, the entire batch may be infertile.
- Incorrect water parameters – If the water is too hard, the sperm cannot penetrate the eggs as it should. This is when the entire batch turns out infertile. Cold temperatures may also arrest or hinder development.
- Stress – If your fish are stressed out, they may eat their eggs as a defensive mechanism. That’s right, they’d rather eat their eggs than have something else eat them!
If the eggs hatch successfully, the parents will guard and feed the fry for the first few weeks of their lives. They do this using a special mucus that forms on their skin, called “discus milk.”
At the end of the first week (around day six after hatching), you can start feeding them brine shrimp nauplii twice a day.
During the first four to six weeks, it’s absolutely essential that you do regular water changes, and deactivate the undergravel filter if you’re using one. With small fry, an undergravel filter can unintentionally break their spines, leading to many deformed and dead babies.
While doing water changes, make absolutely certain that the water is the same temperature as the water in the aquarium. Sudden temperature changes can send the babies into shock, and kill them within hours.
Pro tip: It’s better to do frequent smaller water changes (around 10% daily) when you have fry, than to do larger changes and risk causing shock.
From around the third week of their lives, you can add small organisms like Daphnia and Cyclops to the babies’ diet. Around week four, the parents will ‘wean’ the fry, and stop producing mucus.
If your pair isn’t eager to breed again immediately, you can safely leave the young with the parents. However, if the parents lay more eggs, they’ll see the older young as a threat. If that’s the case, move the first batch of fry to their own tank with similar conditions.
At around six to eight weeks, you’ll have lost most of the weaker young. You can then sell or rehome the remaining fish if that’s your intention.
We hope that this article about the discus has helped you! Like most fish, they can be hard to keep if you don’t understand their needs.
If you keep a shoal of discus in a clean, planted tank with soft, acidic water, they’re easy to keep. Once you’ve mastered their general needs, they may even reward you with some baby discus!
Remember, feed a balanced diet, and do regular water changes.
If you enjoyed this article, you can visit the collection of our posts here.
About the author
AboutHi, I’m Johanan! I love animals of all shapes and sizes, but especially fish. I’ve gone from working at a pet store as a teenager to keeping and breeding Bettas and other fish at home. My passion for fish is endless! the author
You can find my articles here.