Caring for Discus Fish On Freshwater Aquariums

For those who believe that freshwater aquarium can’t match marine in regards to brightly colored fish, I want to introduce you to the Discus fish. Native to the Amazon river basin, Symphysodon is a genus of South American cichlids native to the Amazon river basin. With a distinctive disc shape and bright colors and patterns, the discus are a favourite fish among fish keepers who also refer to them as pompadour fish. However, they have some pretty specific requirements so keep reading if you want to keep Discus on your freshwater aquarium.

Setting Up A Discus Tank

The native environment of a discus fish are shallow streams and small lakes around the Amazon river and its tributaries. Their vertical stripes allows them to blend with the submerged tree roots near the shore that they prefer. As most south american fish, the discus enjoys soft and acidic water. However, most of the discus fish stock that you can buy at fish stores is captive breed, and as such they are more tolerant of less-than-amazonian water conditions that you’d be led to think.

Brightly coloured red Discus fish
Brightly coloured red Discus fish

Discus fish prefers a temperature between 28C to 30C, which is hotter than many other popular freshwater fish such as guppies. They are a shoaling fish, which means having a single, lonely Discus is a terrible idea. It may live, but it won’t thrive and it won’t be happy. Since the Discus are relatively big fish, you will need a large aquarium so they can swim and play around. An estimate of 10 gallons per Discus is preferable, and you will most likely need at least 6 Discus per tank in order for them to feel safe. An exception to this is a paired breeding couple, which should be kept on their own as they become really territorial. Air stones are often needed, as the high temperatures mean the natural oxygen content in the water can become too low.

Before adding fish the aquarium needs to be cycled. Since Discus prefer acidic water and aren’t a hardy fish, the best way to cycle a discus aquarium is doing a fishless cycle. Keep in mind that at low pHs Ammonia will become Ammonium, which is not useful as bacteria food. Remember to do a water change before you add your fish to your newly cycled aquarium!

Discus Water, and the RO Debate

English: Discus fish (Symphysodon aequifasciat...
English: Discus fish (Symphysodon aequifasciatus) at The Pet Fair in Myyrmäki Hall, Vantaa Suomi: Kiekkokaloja Lemmikkieläinmessuilla Myyrmäkihallissa Vantaalla (Photo credit: Wikipedia)

Discus are picky about their water, there is no two ways around it. However, while this may have been a problem in the 80s and 90s when a large part of Discus literature was written, it doesn’t mean you can’t keep Discus on a modern aquarium unless you are an expert. Technology and filtering hardware has evolved a lot since then.

While Discus prefer soft, acidic water, and are more comfortable when they have it, they can live and thrive in slightly alkaline water which is calcium rich. Asian Discus fish are generally more comfortable on very soft, acidic water and if you intend to breed them you will need to provide that environment. But if all you want is a happy shoal of Discus in your tank, as long as your water is not extremely hard or alkaline you should be fine provided you choose European bred specimens.

It is worth keeping in mind that Discus are incredibly sensitive to dissolved metals and impurities often present on domestic tap water. Chlorine and metals need to be removed and this is why most people keeping Discus will suggest the use of either RO water or a carbon filter.

Always keep in mind that fish dislike change. If you want to produce the best tank setup for Discus just ask your breeder and try to match their water parameters and water changes routine in order to minimise the stress of your fish.

Discus are delicate fish, but nowhere near as delicate or difficult as they used to be thanks to modern equipment and a better understanding of what makes fish healthy. However, if you are very unexperienced, other beginner friendly fish may be a better option.

Desirable Water Parameters For Keeping Discus Fish

  • 0 Ammonia, 0 nitrite, low nitrates (fully matured filters)
  • pH between 6.3 and 6.5, but can be up to 7 depending on breeder and stock condition
  • KH and GH between 3 and 4
  • Temperature: 28C to 30C
  • TDS/Total dissolved solids: Around 125

Discus Breeding and Discus Reference Books

Discus fish with young
Discus fish with young

If you want to keep and breed Discus fish you will need to inform yourself and plan ahead. Discus breeding requires pretty specific water conditions, including very slow moving water and pretty low pH. Discus are really fun fish to bred. Not only they form stable, bonded pairs (that will chase everybody else from their side of the aquarium) but they take care of their young and are very good parents.

It is worth getting your hands on some Discus literature such as  Discus Made Easy or The Golden Book of Discus Fish Care to keep as reference. You can always go to your local library and borrow books but I find it useful to have at least one Discus guide within easy reach for reference.

Bare Bottom Tank Or Planted Discus Aquarium?

Discus are cichlids, and as such they are messy. This is why most breeders will keep them in bottomless aquariums that are easy to clean. A planted aquarium is fine provided you are happy to do the extra maintenance and you seal any bog wood to prevent tannins leaching into the water.

If you use a planted tank to house your Discus keep in mind that you will need to provide your plants with at least 10 hours of light per day, which can be a bit too much for the fish. Choose lights that have full spectrum, like T5s, and if your Discus aren’t used to it increase the light amounts gradually.

Incorporating some algae eaters to your Discus aquarium can help greatly with algae control and maintenance, as Discus are pretty messy fish.

Feeding Pompadour Fish

Discus enjoy a varied diet and will spend all day looking for food. In fact, they are pretty big eaters, which means many people underfed their fish who then become much more sensitive to disease and parasites. Feeding them 3 times a day is perfect for their small stomaches and constant grazing for food, but make sure you only feed them what they can eat in about 5 minutes.

There is a popular Discus myth that states that they will only eat red foots. If you give it a try, you will see yourself that it’s nonsense. Pompadour fish will eat prepared flakes, brineshrimp, mussel, whiteworm, beefheart mix, live food, frozen food… just try and see what they do.

Help! My Discus Is Not Eating!

If your Discus is not eating, there is most likely something off with it. Check out the water parameters and ensure that they like the location of the tank and have safe places to hide and no other fish stressing them out.

Sometimes you may find yourself with a case of worms, which means you will need to treat your Discus with a deworming medicine. However, this is uncommon if you only feed them dry and frozen food and no live food. Some of the internal parasites that affect Discus are:

  • Hexamita
  • Roundworms
  • Capillaria
  • Threadworms
  • Tape Worm
  • Metacercaria
  • Sanguinicola

How to Introduce New Discus To Your Aquarium

If you are introducing young Discus to a brand new aquarium (after cycling it) it is better to add several at the same time. Recommended number is at least 6 of them. First of all, Discus are shoaling fish so they feel better when they are surrounded by similar tankmates. Secondly, Discus may be territorial and aggressive towards new arrivals, so moving them all at the same time reduces the chance of aggression. Most Discus won’t eat until they are settled down, which can take a few days, so keep offering them food once a day until they start eating, and then feed them at least 3 times a day. A tank providing plenty of cover, plants and bog wood will help your new Discus feel safe and secure quicker.

Discus are pretty delicate fish, and introducing new Discus from different breeders without a quarantine tank is like playing Russian roulette with your existing stock. Most people recommend never mixing stock from different providers, particularly mixing Asian and German bred Discus, as one of the groups could have parasites the other group has no resistance to. This could end up with many dead fish, so it’s better to play it safe.

Discus are some of the most colorful freshwater fish, and with the right care they will be happy in a large aquarium with soft water. They are not the easiest fish to keep, but their reputation for being only for experts is without a doubt an exaggeration. If you want to stock your aquarium with discus fish don’t let them fear of complications stop you, as they are a lovely fish to keep which will happily interact with you and eat from your hand. As tropical fish goes, they are one of the most amusing to have in your tank, and the bright colors and patterns make them all the more interesting. This is probably why discus breeders often say the lovely pompadour fish is addictive.

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