A Basic Guide to the Care of Discus
by Al Sabetta, August 2003, revised October 2008
This guide is not meant to supercede, or replace any of the comprehensive textbooks written on the subject of keeping fish of the genus Symphysodon spp. Commonly called Discus. It is meant as a primer for those considering keeping this beautiful fish and possibly breeding them. It should be used as a very basic guide, as that is all it is intended to be. I should also preface this work by stating that this guide is based on what the author has found to be useful, and it may differ from what others do or advise.
Discus are cichlids of South American origin that belong to the genus Symphysodon. They evolved in the warm tropical rivers of the Amazon River system. Where they inhabit soft, acidic water that has little aquatic vegetation. The tributaries and small river systems they call home are seasonally flooded, carrying the water into the surrounding forests where the Discus can encounter submerged terrestrial plants, shrubs and trees.…It’s a very unique ecosystem driven by the worlds largest freshwater river system and an incredible flux of water from the seasonal tropical rains.
Wild Discus include several main groups; Greens, Blues,
Browns, and Heckels. The exact separation into species is being currently
revised. For our introductory purposes here, wild discus were captive bred
decades ago. Although wilds are still collected and even bred, the vast
majority of discus in the hobby are domestically bred and raised. Discus have
been considered by many to be the crowning jewel in any aquarium hobbyist’s
crown. To successfully raise and breed these beautiful fish is not the easiest
thing to do, but it is possible if you keep in mind what they need. In the
simplest terms, discus require good clean water, appropriate diet, temperatures
that are warm enough, and good physical health to thrive.
What I will write here will conflict with much of the older works on Discus. Discus evolved in waters that are very soft, and acidic. Because of this they earned a reputation for needing to be kept in that water. Cited often is water in the range of 5.5-6.8 pH, and low TDS (total dissolved solids). This may have been the case in the past, and is certainly beneficial for discus. However, what many hobbyists and breeders, including the Author, have found is that although Discus do well in waters with these parameters, domestic discus are remarkably adaptable in their water requirements. This may be the result of generations of captive breeding and selection, no one can say for sure but it has made keeping these wonderful fish much easier. Young discus will grow fine in water that is between pH 7.0 and 8.0, with some raising them in water that is higher than pH 8.0. This water can have a high kH and high gH and it will still be suitable for any non-breeding discus. Discus that are to be bred will spawn more readily in the softer waters, and lower pHs. Many have noted decreases in egg hatch rates as the waters hardness goes up. To compensate for this, breeders not blessed with soft water make use of Reverse Osmosis water filters, De-ionized water, or Peat filtration. These allow for the removal of the minerals, and subsequent softening of the water. With so many ways to manipulate ones water with a little research, keeping and breeding discus has never been easier.
What water parameters are important then? The water should have no ammonia, and should be free of nitrites, It should have little to no nitrates as well. This is accomplished by having an adequately cycled biological filter. This filter is colonized by bacteria that breaks down ammonia and nitrite waste into nitrate. The nitrate is then removed by any plants in the tank, or by water changes. There is a wealth of information on the internet and in books on biological filtration. If you are not familiar with this area of aquarium keeping, do not undertake discus keeping yet. Discus do not tolerate ammonia and nitrite levels well. Even nitrates which are well tolerated by many species of fish have been implicated as stress factors for discus.
Another important water parameter to pay attention to is your pH. Discus will live in waters within a broad range of pH. Like most fish though they do not like fluctuating pHs. Stability is important. Fluctuations in pH be can be caused by many things…but often occurs when water is added straight from the tap to the tank. Often this water contains gases that artificially raise the pH . Once the water is in the tank though, the gases leave the water, and the pH drops. Depending on the magnitude of the change, Discus can get very stressed. It is very important that a person understand their waters parameters. To do this, a pH reading should be taken right from the tap, and then some water should be "aged" and a new reading taken. "Aging" the water is accomplished by using a suitable holding container such as a plastic pail, or drum. The water is heated and aerated or circulated by pump. This causes the gases to leave the water, and the resulting water will have a pH that is a more true reflection of what a hobbyist’s water really is. Once you know exactly what your pH is, you can make adjustments where needed in your waters kH and gH. It should also be noted that anyone keeping fish has a responsibility to learn about basic water chemistry. There are many online sources and textbooks that cover the relationship of pH, GH, KH, and alkalinity. These topics are outside the realm of this article, but ones that must be learned to avoid unnecessary fish losses.
Water must be clean and free of any chlorines, chloramines, and municipal water treatment chemicals. Commercial preparations are available to detoxify and neutralize these agents. Be sure if you have city/ municipal water that you check with them about exactly what is in that water.
Discus aficionados are notably fanatical about their fish tank’s water. There is great variability though in exactly what is defined as clean water. On one end of the spectrum is the discus keeper that maintains their fish in planted display tank with substrate bottom and changes small percentages weekly. On the other end of the spectrum is the keeper that maintains their discus in completely bare tanks, and does 30% or more water changes a day. There is great debate as to how much water should be changed, and this issue can't be addressed here. As a general guide, change as much as you can daily or at some other interval that you feel comfortable with. If your tanks look dirty, smell dirty, has detectable ammonia or nitrite, has high levels of nitrates, or if your discus are dark, and stressed out…. try increasing how much you change and the frequency. The cleaner your water, the happier your fish will be. Incidentally, I’ve made reference to Nitrate levels….defining what High Nitrates are is not easy….again there is great debate…so I can only say what I consider high… any levels above 20-30 ppm nitrates to me is high for discus….My gold standard is to attempt to maintain nitrate levels less than 20 ppm, ideally less than 10 ppm…thru water changes, and plant uptake.
Diet: Discus are primarily carnivores and as such they require high levels of protein in their diet. This food can be in the form of commercial food, freeze dried, frozen or live. Unfortunately, we do not know what the actual nutritional requirements are for discus and so can only generalize. Because of this the key to success is for the diet to be varied. A varied diet ensures that the fish will not suffer from a nutritional deficiency. It also will give them a better shot at reaching a large size. Given a proper diet, its not impossible for a discus to reach a size of 7-8 inches tail to tip. Often the feeding strategies used are to feed 3-5X a day, remove all uneaten food and wastes. Foods need to have a high protein content, especially for juvenile discus. Numbers cited for percentages of protein range in the 45-50% for juveniles. Percent protein values are not solely important; the types of protein matters, as does the types of nutrition like fats and lips, vitamins, etc. Some types of food commonly fed discus …..
Discus are a tropical warm water fish, coming from the Amazon River Basin in South America. They require temperatures that are higher than many other aquarium fish. Generally fry and young actively growing fish are kept in water that has a temperature range of 84-88 F. Breeders are usually kept in slightly cooler water in the range of 81-83 F. Because of the water temperatures in the Amazon, discus evolved able to tolerate relatively high water temperatures. Often water temperatures in the low 90's (92F) are used to stimulate a fish’s appetite by increasing their metabolism.
If a discus is healthy, its immune system will be able to fight off many pathogens. If the fish becomes ill, it may be necessary to intervene with medications. There are many diverse opinions about the use of medications with fish. Some only medicate when absolutely necessary, other practice prophylaxis for common discus pathogens like Flukes, and worms. The decision of when to use a medication is a personal choice, but it is a choice that needs to be made in an informed manner. Be sure your fish needs to be treated, and be sure you know everything about that medication or seek qualified advice. Used wisely medications can save a valuable fish, used carelessly or ignorantly and they can destroy your biological filter, create resistant pathogens, and kill fish.
Disclaimer… The views expressed in this article are the opinions and experiences of the Author…They are offered as such and nothing more. Thank you, Al Sabetta, Oct2008
This article is copyrighted to Al Sabetta, Oct 2008.