Discus Fish Aquarium Requirements & Set Up

By Nadine Oraby | 2020 Update

With beautiful patterns and vibrant colors, discus fish can add a lot to your aquarium aesthetics. There’s no surprise that these beautiful fellows are a bit high maintenance.

Discus fish come from the Amazon and it is very important to provide them conditions similar to their natural habitat. From the size of your aquarium to the temperature and pH level, everything needs to be properly maintained to ensure the wellbeing and survival of your discus fish.

The Amazon, as you may already know, is no ordinary river. The water is slightly muddy, warm, and acidic. It is also soft water, which is why most people recommend a Reverse Osmosis filter for a discus fish aquarium.

I know that sounds like a lot of prep but a healthy and happy school of discus is truly worth all the efforts.

How to Set Up a Discus Aquarium (Video)

Water conditions – Replicate discus fish’s natural habitat

When setting up a discus fish aquarium, think “Amazon”. Located in South America, the Amazon is truly a one of a kind river of this planet. The water quality and condition have turned it into the home of numerous unique land and water species. Discus fish is one of them as it wasn’t found anywhere else in the world before fish farms were created.

Now, we know that Amazon water is warm and acidic. That’s how discus fish like it. So, set the temperature somewhere between 82 to 84 degrees Fahrenheit. Your fish will be fine with up to 88 degrees, though. In fact, many enthusiasts believe their fish tend to be happier and more active when the temperature is between 86 to 88, it all comes down to personal preferences, I suppose.

To replicate the Amazon’s conditions, you need to set the pH between 6 to 7. There are places where tap water is soft enough but many pros recommend mixing tap water with water from a Reverse Osmosis filter, just to be safe. Softness of the water is even more important when you plan to breed your discus fish. Hard water can harden the eggshell and it makes it impossible for the fry to break it. Many fry might die in the process.

Aquarium size – Discus fish need a large space to flourish

In terms of volume, Amazon is the largest river in the world. This means that your discus fish is used to a huge boundless home. It is understandable that your aquarium isn’t exactly boundless, but a bigger tank can create that illusion for your fish. This will keep your discus fish as happy as they are in their natural habitat.

Since discus are schooling fish, they tend to stay in a group of four to six. Each fish can grow up to six inches in their natural habitat and much larger in captivity. Now imagine that big a group roaming around in an aquarium. Even a 29-gallon tank would be too small for free fish movement.

By that calculation, most hobbyists and experts agree that you need an aquarium with a capacity of at least 50 gallons, and ideally one with 120 gallons. The aquarium should be both high and long because a discus fish grows just as much in height as it does in length.

Make sure you have decided on the number of discus fish you wish to keep before you set up an aquarium. Decide on the tank size accordingly. Once the fish are in the tank, it isn’t healthy or safe to transfer them to another one. It can stress them out and they might fall sick. So, make sure the aquarium is big enough to begin with.

Lighting – Be careful with that thing

Lights can really bring out the beauty of discus fish’s bright colored patterns. Fluorescent lights above the tank will do the job, but can just as easily overdo it. 2 to 5 watts per gallon is usually recommended.

Think of the Amazon River!

The water is usually muddy and discus fish prefer areas with floodwater because it is even darker. Too much light is never a good idea for them. You need to keep in mind that they aren’t used to too much direct sunlight either. So, do not place the tank near a window or doorway.

You can block out the unwanted light by painting the bottom and sides of the aquarium. You can even get an aquarium with tinted glass that doesn’t allow too much light from the sides.

Speaking of tank placement, it is never a good idea to place it at a spot where there is a lot of movement or in a high traffic area such as corridors. Sudden and frequent movements can scare your discus fish and will stress them out. And as you know, a discus can easily fall sick when stressed.

Plants and décor – Less is more

That doesn’t make much sense, right?

We all know Amazon has plenty of plants- but it isn’t easy to find plants that can thrive in the water conditions you just created for your discus fish. Many fish keepers fear that plants and substrate will mess with those conditions and it will be difficult to maintain the aquarium. That is partially true.

Discus may not hate you for keeping them in an empty aquarium, but they won’t be too happy either. Besides, an empty tank doesn’t really look good. You can plant Java Ferns, Water Sprite, and plants that can actually control the nitrate level in the aquarium. If anything, they will actually support your maintenance endeavors.

For substrate, a thin layer of fluorite wouldn’t cause any inconvenience. Sand is also a good option because discus fish like to play with it sometimes. Like it or not, discus fish would appreciate good places to hide, especially if there are other tank mates present.

My best advice is to not skip on plants and decorations even if they take frequent maintenance. There is no reason to keep a fish if you can’t invest enough time on its happiness.

Filters – Keep nitrates and ammonia under control

High quality filters are crucial for the maintenance of water parameters in a discus fish aquarium. You need both mechanical and biological filters to make sure the nitrate and ammonia level is always minimum. I usually recommend a combination of a canister filter along with a sponge filter.

One great advantage of a canister filter is that it can be filled with different media to maintain different water conditions. Find one that suits your discus fish requirements.

Also, remember that the Amazon isn’t exactly a fast-flowing river so discus fish aren’t used to fast flow. That is why you should steer clear of overpowered filters.

Changing water – Survival essential for discus fish

In order to keep nitrates and ammonia levels under control, you need to change discus fish’s aquarium water more frequently than other fish. 25-50% percent of the tank water should be changed every week.

People would tell you that their discus survived 20 percent per week but trust me that fish isn’t happy about it.

Stick to 50 percent weekly because some discus fish tend to be more sensitive than others, especially the young ones. In fact, if you have any juveniles in the tank, it is likely to get much dirtier as the young ones eat and excrete more often. I must also add that some amateur aquarists often make the mistake of changing all the water at once. This can be counterproductive. You will do more effort for virtually nothing.

Don’t skip water changes for your discus fish as they are very sensitive to contaminants in the water. They can fall sick immediately, and eventually die within weeks of such terrible neglect.

Tank mates – Pick the best pals for your discus fish

Like most schooling fish, discus are shy when it comes to socializing with other fish. It doesn’t mean they aren’t peaceful or they like to live alone. We are talking about Amazon natives here! That river is full of diversity and discus are used to living with other species.

Sadly, they are so well behaved and peaceful that an aggressive species such as angelfish will eat all of their food without much counter-resistance. So, that isn’t a good idea.

Keep your discus fish away from any predatory fish for that matter, as the former don’t fight back and you are likely to see a lot of nipping.

It is best to keep them with schooling fish such as tetras and characins. Having another school in the tank can have a calming effect on your discus fish. There are many other fish that gel well with discus but most of them aren’t used to warm waters.

On the other hand, there are fish that are peaceful tank mates for discus and can even survive the warm water, but they are messy and can easily disturb the water conditions of your aquarium. Some fish are also likely to introduce parasites to your discus, so you need to be very careful.

All I can say is, it’s important to keep your discus safe from bad company.

Disease prevention – Ensure a safe environment

There is a reason why people say that discus fish isn’t an easy fish for beginners.

Discus are susceptible to numerous diseases, most of which are related to poor water quality. The good news is that they are easily preventable with a little prudence.

Ectoparasitic infestation is among the most common health issues for discus fish. This will cause irritation, red skin, and breathing problems in your fish. You are most likely to find them rubbing against a rock or flicking. A de-wormer is usually sufficient for the treatment. You will also need to change the water and clean the sides of the aquarium.

Red skin, swollen bellies, and protruding eyes are also common symptoms of bacterial infections. You can treat it by adding an antibacterial agent after cleaning the tank.

If not treated on time, even minor infections can lead to bigger problems such as rotting fins and discus plague. Other fish can easily catch these diseases from one sick discus. Before you know it, all your fish will be dead.

Nitrate poisoning is also very common as discus fish are extremely sensitive to high levels of nitrates in the tank.

Now, I will say it again; with more even emphasis; always monitor and maintain the water quality and condition in your discus fish aquarium.

Food – keeping your discus healthy

Despite the best water quality and tank conditions, there is one thing that can still make your discus fish unhealthy or unhappy – the food.

People seem to be quite confused as to what they should feed their discus fish. Many would say that you should limit their diet to high protein meat. However, it is good to keep top quality flakes and pellets in rotation as well. Any fish would appreciate variety.

Many people often argue that a meat-only diet will help the discus grow bigger. It is true that such a diet can actually make your discus grow as large as 9 inches, but size isn’t the best indicator of health. A good diet that includes variety will keep your fish more active and happier. That’s very important for their wellbeing.

Do not feed them low-quality fish food or food that is expired or has gone bad. As I have said earlier, this is a very sensitive fish you are dealing with. You need to take care of them like you would care for a newborn baby.

The most important fact

Lastly, I would like to bring your attention to one of the most important facts about any fish. Always talk to the person you bought it from and discuss the conditions your fish are used to.

Discus fish is extremely popular across the world and many people have managed to accustom them to different conditions. While I have clearly defined the ideal conditions you require to set up a discus fish tank, it is possible that the fish you bought are used to different conditions.

Take your time and ask your vendor all the questions related to the conditions, diet, filters, size of the tank, and even tank mates.

It would be best to recreate the same environment and replicate the conditions they are already used to. This will put less stress on those little fellows, and you won’t have to put up with trial and error.

The more you know about the fish you bring home, the better you will be able to take care of it.

Related questions

Do all discus fish come from the Amazon? Discus fish are originally from the Amazon. Their population was initially limited to the lower reaches of Rio Negro. Later on, aquarium exporters introduced the fish not just in other parts of the Amazon, but also in other parts of the world. There is a huge market for discus in Asia and many countries have their own breeding farms from where they are exported across the world. There is a well-known German Discus called Stendker, which is often preferred because it can grow bigger and stronger.

How long does a discus fish live? With proper maintenance and care, a discus fish can live for as long as ten years in an aquarium. However, they are sensitive fish and require adequate water conditions and proper nutrition. They do not survive well in the presence of any aggressive or predatory breed of fish. In ten years, a well-fed discus fish in a spacious aquarium can easily grow up to 9 inches.

Do discus fish breed easily? No, Discus fish don’t breed easily. They usually mate for life and it is not easy to find a mating couple. When they have successfully mated, the female can lay up to 200 eggs, only a handful of which hatch into fry. Discus fish fry require a lot of care from their parents and the keeper in order to survive and grow.

How to tell if a discus fish is sick? Discus fish is a sensitive breed. They need perfect water conditions and minor neglect can make them sick. When a discus fish is sick, the symptoms are almost immediate. The fish will stop eating food and will seem lazier than usual. Swollen belly and protruding eyes are also signs of sickness due to high nitrate levels in the tank. If the fish is rubbing itself against the rock, it can be a sign of an infection. Some discus diseases will also change the color and texture of their skin. Keep an eye on such unusual symptoms.

How to tell the difference between male and female discus fish? Discus may be the most challenging fish to distinguish between both the sexes. There is no clear distinction between a discus male and female. A fully-grown male tends to be heavier and bigger than a fully-grown female. Male discus has a pointed dorsal fin while a female has a rounded one, but this difference isn’t always too clear. However, once you have a school of discus in the tank, you might be able to tell the difference by noticing their behavior. Any vendor who tells you the gender of a discus fish smaller than 4 inches is definitely lying about it.

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