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Fish, Shrimp & Corals


December 13, 2018 | By Tom Sarac

by Tom Sarac

The discus, also known as the king of aquarium fish, have been so intensively bred that the vast array of colours available has become almost dizzying. I have had the great privilege of visiting some of the most impressive discus breeding facilities around, namely Jeffrey and Tony Tan’s Malaysian discus breeding facility. Here, I saw not only a surgically clean breeding facility, but discus of quality that I had only ever dreamed about. For those of us who have some knowledge of the wonderful world of discus, the mere mention of the Aquarama Show in Singapore would quickly equate to the Tan brothers to absolutely perfect, show-quality discus entries with a winning history.

To say that the selectively-bred strains of discus are where it begins and ends would be amiss. With their hardy disposition and intact instincts, plus many stunning variations, wild discus have a place in every true enthusiast’s heart. That said, when one is fortunate enough to have a pair of wild discus spawn, it is something to be cherished. Trust me, I speak from experience when I say that.

When it comes to keeping discus, which is almost unavoidable when one is first introduced to these regal fish, there are some important practical points to consider. The basics can be broken down as follows.


You should endeavour to keep adult discus at a fish to volume ratio of one to every 40 L (10 US Gal), and younger fish at a ratio of one per 20 L (5 US Gal). Discus are fish that naturally school in nature, and feel comfortable within a group of their own kind. This is easily observed in any aquarium containing discus and in films or photos of discus underwater.

In fact, you may even notice that discus kept in smaller groups can be more nervous. A real school of at least 6 or more specimens in an adequately-sized aquarium would make them more comfortable.

For breeding purposes, discus are typically housed in approx 75 to 115 L (20 to 30 US Gal) tanks at most. This is so the fry can easily find their parents as they first start to feed. Life for discus fry means instinctively being close to one another. This is for both their protection and their care, and it seems this preference or conditioning remains with them as they grow.

When it comes to discus versus aquarium size, be sure to move the fish up in aquarium size as they grow.


Discus are classified as warm water tropical fish and should be kept within a range of 28°C (82°F) to 30°C (86°F). Typically the lower of these two values is preferable for most discus, while the higher part of the temperature range is better in the case of certain disease treatments and for specific types such as the Heckle discus.

Given the fact that discus prefer warmer temperatures, if considering keeping live plants with them, you should be aware some plants don’t do well in water temperatures over 28°C (82°F), so make sure to keep this caveat in mind before finalizing which plants you intend to keep. The same goes for any fish mates because many species are at the top end of their temperature tolerance at the range discus range discus prefer.

Consistency is equally important, and any changes should be done gradually. When performing water changes or doing anything that could affect temperature, make sure it is minor.


Water changes, water conditioner and hygiene are key when discussing discus health and long-term success. This part of the equation does not change. Frequent and with regularity is what best describes a water change schedule for discus. A good suggestion is 20 to 25% per week, but more is better if you can handle it.

Equally important is paying attention to the pH and KH of the water you are using for water changes. Discus can often do well with tap water, especially if they have been locally raised in it. This does not mean you take things for granted, however. Test for pH, KH, ammonia, nitrite and nitrate, and make sure that things such as seasonal fluctuations or municipal water management strategies have not had any impact on tap water characteristics in your area.

In general, the best advice when deciding what pH and KH you should have for the discus you are going to get is to mimic the values from where they are coming from. When being transferred from one environment to another, please remember this point. Discus do not tolerate sharp increases in pH well, so find out the pH and KH of the water they were originally being kept in. Take your time and drip new arrivals for at least 30 minutes to ensure you have substantially reduced any potential stress.

Also of great importance in doing what you can to keep a hygienic discus environment is wiping down the interior glass surfaces of the tank. Invariably, there is a bio-film that forms on it and it doesn’t take long to happen, so wipe down weekly if you can.

The use of an ultraviolet sterilizer certainly has an application in a discus tank, and will help control undesirable species of bacteria as well as certain very small parasites.


In many cases discus evolved in river environments and, therefore, the water movement in your aquarium should not be overly strong, but should provide some current. Don’t expose young discus to stronger flow but as they get larger, you should increase the flow rate.


The best tank mates for discus are – other discus. For some people, variety is non-negotiable and to this I can only recommend choosing species that prefer warm, softer acidic water conditions, are calm fish, not nocturnal, and will not be overly competitive feeders that the discus have to constantly contend with. There is also the issue of disease importation with other species of fish. When it comes to domestic strains of discus, remember quality, domestic discus are usually raised in very clean and controlled conditions. Discus prefer feeding off the bottom, which makes them more prone to picking up intestinal parasites.

All that said, if one is adamant about keeping discus with other species of fish, practically speaking I would then seriously recommend going with wild discus, and keeping them with some of the species that would normally co-inhabit in an actual natural habitat.


Beyond water changes, feeding is the area where you can really make a major difference in both the health and the condition your discus will exhibit. Variety is important. Give at least several types of frozen food, bloodworms, mysis, complete frozen discus mix and glass worms, and at least one or two types of quality sinking discus pellets. Flakes have their place too. Most discus relish quality dry foods, which also helps them take in a balanced formulation, infused with vitamins and other key nutrients.

It is preferable to feed discus several times a day the amount they consume in up to 2 to 3 minutes. Equally important is removing any uneaten food right away. As stated, discus are bottom feeders, and it does not take long for potentially harmful parasites or bacteria to end up on uneaten food, which could end up entering the gut of the fish. Remember hygiene here.

Having kept many discus over the many years I’ve been a dedicated aquarist, I hope after reading this you’ll find my advice to be helpful. I’ll finish up by encouraging you to be patient, to select quality fish, set up the ideal environment, and dedicate yourself to water changes and the basics that discus require. The king of the aquarium will never cease to impress you.




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