Admin Note: DiscusPaul has very kindly offered this in-depth article for free for our members. It is included here in full as well as a PDF attachment (BeginnerDiscus.pdf). Enjoy!
Greetings to all you discus fans out there,
I'm retired, living in Vancouver, B.C., and have been fish-keeping on and off, both fresh and saltwater, for over 50 years, since I was a kid. At one time, I had about 15 tanks, and bred many varieties of egglayers, Tetras, Barbs, Danios, Angels, Bettas, Gouramis, and others. That was mostly in the late 1950's and 60's when LFS's would only give me .10 cents each for 3 month old fry. My, times have sure changed.
But my life-long love has been discus !
I belong to 5 other aquarist forums, and found over the past year or so, going through many Stickies, threads & posts, that there didn't seem to be any one single place where someone interested in discus could get a reasonably inclusive step-by-step outline as to what needed to be done to properly get started with discus.
So I decided to write a reasonably comprehensive guide myself, to give any discus newcomer the necessary tools to launch him or herself into discus-keeping, in the safest, most successful manner possible.
My guide has already been posted on some forums, notably simplydiscus.com and the U.K. bidka forum (British & International Discus-keepers Assoc.), but it seems that my favorite forum these days is Planted Tank, which I have noted has many member discus-keepers - experienced, just new to the hobby, or wannabes.
Administrator Kyle kindly accepted my offer to have PT post the guide, and I am delighted that it will be available to PT's strong, active, and seriously committed membership !
Best of luck with your entry into the fascinating world of what is, arguably, the most beautiful freshwater aquarium fish.
Please don't hesitate to call on me if I can be of any further assistance to you along the way.
Beginner’s guide to getting started with discus
Written by: Paul Villeneuve
Edited by: Martha Morris
Photos courtesy of the author,
Martha Morris and
1. S. Discus Heckel - 2. S. Aequifasciatus (green discus) - 3. S. Haraldi (blue and brown)
Wild discus inhabit some of the tributaries of the Amazon River in South America. They usually live in large social
groups in shallow river, stream, or creek beds of slow-moving water near the banks where tree roots protrude, providing
cover. Vegetation hanging overhead provides shade from the bright light. The water temperature is generally constant in
the 27 to 29 Celsius ( C ) range (low 80s Fahrenheit (F)} . The pH is acidic, usually in the range of 5.0 to 6.0. The water
is very soft as it contains very small amounts of dissolved minerals. These conditions differ significantly from the
environment usually found in home aquaria but the discus have adapted well. For instance, domestic discus have shown
they are able to thrive in steady but wide-ranging pH levels, up to 8.0. They have also done well under consistently
stronger lighting conditions, and in heavily planted environments. However, all discus remain largely intolerant of poor
water quality, or water temperature below 27 C (81 F).
Figure 1 Nhamunda Red Wild Discus
There was very little known or written about discus until after the middle part of the 20th century, and it wasn’t until
around the 1960s that hobbyists in various parts of the world began breeding wild-caught discus. After that time, a good
deal of information began to emerge about keeping and breeding these marvelous fish. In the 1970s and 80s, there was a
proliferation of breeders who established discus fish farms for local and export sale, mainly in South East Asia and some
parts of Europe, particularly in Germany. By 1990, many new and colorful varieties of this intriguing fish had been
Discus are one of the most graceful, interesting, and arguably the most beautiful of all freshwater tropical fish. The
fascination of keeping and raising these magnificent fish has taken the aquatics world by storm, and you’re one of the
many wanting to get started with this very satisfying hobby.
This guide is intended to get you started on the right footing – to enable you to raise the “King of the Aquarium” in good
health, with the least amount of start-up snags and problems.
Here’s how to get started!
A. TANK SIZE
Discus are relatively large fish, growing to 15 centimeters (cm) (six inches) or more at maturity, measured from nose
to tip of tail, and therefore require a good deal of tank space in order to reach their potential and thrive. I recommend
you start off with the largest tank you can afford. This should be no less than 220 litres (L) (55 gal.), but more preferably
in the range of 260-300 L (65-75 gal.). If budget is a problem, buy a used tank.
B. TANK EQUIPMENT
Discus require a temperature range of 28-30 C (82-86 F) in order to thrive. You’ll need to acquire a heater of
sufficient wattage to maintain the desirable temperature for keeping your discus, in accord with the size of your tank.
As a guide, one watt per L should be sufficient– so a 250 watt heater should do nicely in a 220 L tank. As many
heaters only have a maximum temperature setting of 30 C (83 F), it will be very difficult for such a heater to achieve
and constantly maintain water temperature at the maximum setting level. It is best therefore to get a heater with a
maximum setting level of 34 C (93 F). There are a number of reliable makes on the market, so you will have a good
selection to choose from.
There are three types of filtration, i.e. biological, mechanical and chemical.
- 1 - Biological filtration refers to the breakdown of toxic ammonia into nitrites, and then into nitrates by a colony of
bacteria. These bacteria are often referred to as ‘beneficial’, or ‘nitrifying’ bacteria.
- 2- Mechanical filtration refers to the process of removing solid waste matter and other particulates from the water
column. Examples include foam pads and flosses.
- 3- Chemical filtration removes chemical impurities and discolorations and clarifies the water. Carbon is often used
for this purpose.
All three types of filtration can be maintained, or ‘housed’ if you will, in the actual filter container types that you
select for your tank, whether that be a Hang-On-Back (HOB), or canister. A sponge filter will provide for biological
and some mechanical filtration. Your colony of beneficial bacteria will establish itself in or on tank surfaces, but
primarily on and within whatever filter media you elect to use in your filtration container(s).
There are many reliable types of filters to choose from. Many, if not most, discus keepers raise their fish in barebottom
tanks and they usually employ one or more sponge filters, often supplemented by either HOBs or canister
filters, to provide for all their filtration needs. In a planted tank, the preference seems to be to use either HOBs, or
canisters, or both together, and to forego sponge filtration, primarily for aesthetic reasons.
The size of the tank, its purpose, and your preference will determine the needed type, size and capacity of the various
filters which are available to choose from. Capacity is measured by the volume of water turned over each hour. A
complete turnover of at least four times an hour is suggested as being suitable. An example of adequate filter
capacity for a 220 L (55 gal.) tank would be to use a filter rated for tanks up to 300 L (75 gal.), and which has an
average water flow rate of 800 L (200 gal.) or more per hour. This will result in a complete water turnover rate in the
tank of approximately four times an hour.
3. Test Kits and Other Essentials
One of the most important items of equipment you will need are test kits to test your water on a regular basis for the
presence of ammonia, nitrites, and nitrates, and to determine the pH, and general and carbonate hardness levels.
While your local fish store (LFS) will very likely provide a water testing service at no cost to you, this can be quite
inconvenient. With your own test kits, you will be able to quickly check your water parameters at any time. This will
allow you to ensure your ongoing tank care is being maintained as it should, and to determine if your water is the
culprit should problems occur.
Once your tank is fully cycled and ready to house fish, the test for both ammonia and nitrites should read “0”, and
nitrates should be less than 20 milligrams per L (mg/L). Mg/L are synonymous with ppm (parts per million). Your
pH test should reflect a steady, stable maintenance of pH anywhere between 6.0 and 8.0. For discus-keeping, your
water’s general hardness (gh) can suitably be anywhere between a low of “0” to a high of 200 mg/L, whereas
carbonate hardness (kh) should generally be between 40 and 100 mg/L.
You will also want to equip yourself with other essential items, such as a water conditioner to remove chlorine,
chloramines, and other undesirable elements from your tap water. A water conditioner should be used at start-up
when cycling your tank, and whenever replacing water during water changes. As an alternative, you may want to
look into and consider acquiring an HMA filter (Heavy Metal Axe), which is used to remove chlorine, chloramines,
and potentially harmful metals from your tap water. Although relatively expensive initially, many hobbyists find that
an HMA filter is more economical in the long run than continually buying liquid de-chlorinators, and produces
better quality, safer water for their discus.
Other needed items are a thermometer, fish net, siphon hose, 20 L (5 gal.) bucket or pail for water changes, sponge,
scrub brush, perhaps a water barrel for ageing water (a food-safe garbage pail will do), extra filter media items such
as filter floss, foam pads, etc. and of course, some fish foods. If you’re doing a planted tank, you’ll need substrate,
plants, driftwood and/or rocks, etc.
Once you have decided on the size of your tank, you’ll need a sturdy stand to carry the weight. A filled tank, with
substrate, driftwood, etc., will weigh around one kilogram (2.2 pounds) per L , so a 220 L (55 gal.) tank will weigh
approximately a quarter of a ton. Buy a ready-made stand that is specifically designed to maintain the weight of the
type and size of tank you are getting or, if you are going a home-made route, get some expert help to ensure it is
properly braced and structured to accommodate the weight.
As for lighting, you won’t need extra strong, bright lighting for discus. Low light will do, perhaps in the range of
around .25 to .5 watts per L . For a planted tank, this should prove adequate for many, if not most, of the hardy, easy
to grow plants that will also tolerate the higher temperature you will be maintaining for your discus.
C. TANK SET-UP CHOICES
1. Bare-Bottom Tank
This set-up is by far the most preferred approach by both newcomers to the hobby and experienced aquarists alike,
for “growing-out” juvenile discus or for keeping adults. It is generally regarded as the easiest for maintenance
purposes, and the most successful way of keeping discus. It allows you to readily spot any build-up of uneaten food,
fish feces, or other matter, and quickly siphon it off at any time. It makes it easier to undertake more frequent and
larger water changes to promote better and quicker growth of juveniles, to maintain a high level of water quality at
all times, and to more easily clean tank glass, as well as to service or change equipment. A bare bottom tank is easier
to medicate if that should ever prove necessary.
Figure 2 Simplicity of a Bare Bottom Aquarium
2. Planted/Display Tank
This second option can be either discus only, or a “community” type tank with some other species of fish. For the
hobbyist, there is arguably nothing more attractive than a well aquascaped discus display tank. It’s a sight to behold
and could suit you well, particularly if you have previous experience keeping tropical fish in a planted tank
The ratio of fish to size of tank will be reduced in this set-up, given the quantity of water taken up by substrate,
plants and other décor. In this case you’ll want to either increase the size of your tank, or reduce the number of fish
you’ll be keeping. For example, if you were planning to keep eight adults in a 300 L (75 gal.) bare-bottom tank, you
should reduce that number to six in the same-sized planted tank.
Secondly, for your discus’ sake your water temperature will need to be maintained at no less than 28 C (82 F) –
nothing lower will do – and that can pose a challenge for keeping plants, as many varieties do not do well at that
temperature and above. Planted discus tanks entail more work and attention to keeping both elements healthy and
thriving. Your focus will obviously have to be on the discus.
So, if you have no prior experience with a planted aquarium, you would be well-advised to go for a bare-bottom setup,
at least until you gain experience with discus. However, if you do have experience with planted tanks, you
needn’t be fearful of giving it a go if you accept the challenge of the extra attention and diligence needed. It’s certain
you will find it most satisfying and enjoyable.
Figure 3 Example of a planted aquarium
I. CYCLING THE AQUARIUM
You have made your decision as to the size of tank and type of set-up you want, and you have bought the tank, stand,
lighting, and the other necessary pieces of equipment. The tank has been set up in its permanent location in the room, you
have readied the filter, or filters, for operation, and you have placed the heater into the position you want it. If doing a
planted tank, you have also added your selection of rinsed substrate, driftwood, or any other décor, and put your desired
arrangement of plants in place in the substrate. As a last step before plugging in and starting the filters and the heater,
you have filled the tank, at least to a 90 % level, with conditioned warm tap water of at least 28 C (82 F).
It is now important to ensure the tank is cycled. NEVER, never introduce discus to an uncycled, or cycling tank. It can,
and probably will, kill them. It’s cruel and expensive ! ‘Cycling’ can probably best be described as the growth of colonies
of beneficial types of bacteria, called nitrifying bacteria. They are necessary because they neutralize ammonia, convert it
into nitrites, and finally render the nitrites to produce nitrates. Ammonia and nitrites are toxic to fish, whereas nitrates
are much less toxic, and generally harmless in moderately low concentrations. When you cycle a tank, you are really
cycling the filter materials, or media. While there will be some bacterial presence on the tank glass walls, on driftwood
or other decor, and in and on substrate, a majority of the bacteria will likely be in the filter(s), although a good amount
may be located in the substrate. Colonies of beneficial bacteria can only develop and survive in the presence of ammonia.
In a cycled aquarium, these bacteria will maintain themselves in sufficient quantities to render harmless all the ammonia
that is being produced in the tank by fish, and by decaying plant matter, uneaten decaying fish food, etc.
Fresh water from the tap has very little or no ammonia and no beneficial bacteria. One of the more accepted methods of
starting the cycling process, called the fishless method, is to begin introducing store-bought ammonia (NH3) to a newly
water filled tank. Bottled ammonia is readily available in approximately 10% concentration with only water added.
Read the label. It should contain only ammonia and water - no dyes, fragrances, nor surfactants. It should be colorless
and should NOT produce any foam when shaken. You can buy this ammonia at most discount or chain grocery stores or
With the filter on and the heater running, add sufficient ammonia to your tank to produce an ammonia test reading of 4
or 5 ppm. Start by adding five ml of ammonia for every 40 L (10 gal.) of water, or 25 ml in a 220 L (55 G) tank. Swirl it
around and let it sit. Please note that ammonia at the dosage level suggested above is the quantity needed when using a 10
% concentration of ammonia in water. If you’re using 100% pure ammonia, the dosage will need to be reduced
accordingly, i.e., by 10 times, - only six to eight drops of ammonia per 40 L (10 gal.).
Test the ammonia level and add more ammonia if necessary, two or three ml at a time, until a test shows a reading of 4 or
5 ppm. Then test daily or every second day until the ammonia level has dropped to around 2 ppm. This indicates that
bacteria have begun to develop and neutralize the ammonia. Test for nitrites at this point; you should get a reading
indicating that nitrites are present. Add more ammonia, five to ten ml at a time, to bring the level back up to 4 or 5 ppm,
in order to maintain sufficient ammonia in your tank for the growing bacterial colony to consume and survive. Keep
testing for ammonia and nitrites daily, or every second day, while at the same time adding ammonia regularly until the
nitrites have spiked up to a high reading. It will take a few more days for a high nitrite level to drop to a low range, as
the type of nitrifying bacteria that renders nitrites into nitrates take somewhat longer to grow and multiply.
During the cycling process, it is suggested you regularly check the pH of your tank water. A low pH of 6.0 to 6.5 during the
cycle will slow down the development of the nitrifying bacteria colony and perhaps even stall it’s growth. If your pH is
maintained above 7.0 during the cycle this should have the effect of hastening the process.
Over time, when your testing regularly reads a ‘0’ level for both ammonia and nitrites anywhere from 12 to 24 hours
after you have added your last dose of ammonia, you will know that the bacteria levels have developed in sufficient
quantity to deal with the ammonia in the tank. At this stage, the nitrates level will be high. Do a large water change of
75% to 90% to reduce the nitrates to 20 ppm or less. Your tank has now fully cycled and is ready for fish. Remember,
you need to keep adding ammonia in small amounts every day or so while your tank is cycling and the bacteria colonies
are growing, so the bacteria will not die off, until you are ready to add fish to the tank.
This process generally takes around six weeks. Bicarbonate of soda can be added to the water to raise the pH above 7.
This ensures a quicker and more successful cycle and reduces the cycle time by one to two weeks.
One final note, if you’ve opted to begin with a planted tank, consider allowing some further time following the cycle to
acclimate and start your plants’ growth before introducing the discus. A total cycling and seasoning period of 45 to 75
days should allow the plants sufficient time to become established.
The entire cycling process can be eliminated if you can buy a cycled sponge from the discus supplier, or add a seasoned,
colonized filter with all of its media intact from an established healthy tank to your new tank. In this case, fish can be
added immediately. If you do so, test your water daily for the first few days to ensure there is no ammonia or nitrites.
This is to confirm that the size of the bacterial colony you have introduced is sufficient to deal with the fish bio-load you
have placed in your tank. If you add cycled media it should come from the fish supplier or from another tank you have,
not another source like a friend or the LFS.
II. WATER QUALITY
Discus are tougher than a lot of people think and they can be relatively easy to raise and keep healthy if one ‘follows the
rules’. Perhaps the most important of these rules is maintaining water quality at a high level. Discus are more
demanding, or shall we say, more intolerant in this area, than almost all other types of tropical freshwater fish. Here are
the conditions that need to be maintained on a consistent basis.
A. Conditioning Your Tap Water
Conditioning means removing, or neutralizing, those elements in your tap water that can be toxic to fish – mainly
chlorine, chloramines, and other harmful elements. There are many effective water conditioners on the market. Follow
the dosage directions on the container to condition tap water for your initial tank set-up and for all the water used for
water changes. Alternatively, use an HMA.
B. pH of Your Water (Range of Acidity or Alkalinity)
The vast majority of discus available today are farm-bred and raised, and can readily tolerate, if not thrive in, pH levels
ranging from 5.5 to over 8.0. Many of you will find that the pH of your tap water is in the 6.5 to 7.5 range, which is
The key to pH for discus is to maintain a relatively steady level, avoiding rapid fluctuations up or down. Even moderate
fluctuations in pH, occurring quickly, can be harmful, if not fatal, to your fish. pH will very likely change somewhat from
tap, or ageing barrel, to tank, between wc’s, and over time, but so long as this is gradual, there is generally no problem.
The danger lies only when a large change in pH takes place over a short period of time. This is why it is recommended
that beginners not attempt to modify or alter pH levels by using chemicals. If the pH of your water is 7.7, then stick with
that. Resist the temptation to try to change it!
The first step is to test the water coming straight out of your tap. Then, fill a 20 L (5 gal.) bucket with tap water. Let the
water sit and ‘age’, aerated, for a 24 hour period and test it again. Tap water often contains a lot of dissolved carbon
dioxide. When water is released, the carbon dioxide dissipates and the pH then rises. If the pH rises by no more than 0.4,
then it should be safe for you to use water directly out of the tap for your water changes, or for topping up evaporated
water if necessary, but as long as that water is conditioned to remove chlorine, etc., and the temperature is within a degree
or two of that in your tank. If the pH rises by more than this, then the water needs to be aged before doing your water
changes. Otherwise, your fish can experience dangerous, or fatal, pH shock. Many aquarists maintain water ageing
barrels of various sizes, usually in the range of 150 to 200 L (40-50 gal.) or more to accommodate their water changes, thus
eliminating large fluctuations in the pH. Ageing barrels are most often simply inexpensive food-safe garbage pails in
which aquarists store, aerate and heat their conditioned water before doing water changes. Ageing also ensures the
conditioner (or dechlorinator) has had ample time to work. The length of time needed to age the water varies, and it
depends on how long it takes to gas off the carbon dioxide. If the pH in the barrel does not rise further after 12 hours, for
example, then the water should be aged 12 or more hours.
C. Water Changes (WC’s)
Frequent water changes are of singular importance for maintaining good water quality and chemistry – it’s the key to
thriving, healthy discus. If raising juvies, your ideal routine would be daily wc’s of between at least 25%, to 50% or more.
In a smaller tank, you can use a siphon hose and bucket, but you may want a hose with attached pump for larger tanks to
move the water from the tank to the chosen drain outlet, and from the ageing barrel, if needed, to the tank.
Many discus-keepers do well with wc’s of 50% or more every second or third day, while others keep healthy and happy
discus with large, twice-weekly wc’s, ensuring fecal matter and uneaten food is siphoned off regularly as it accumulates.
The efficacy of your filtration will also play a part in deciding on the frequency and quantity of your wc’s. In a display
tank, your plants will assist filtration to some extent by consuming, or utilizing, some wastes, and will help keep nitrate
levels lower. However, the other side of the equation is that planted tanks are a great deal more difficult to keep clean and
spotless than a bare-bottom. Substrate, in particular, harbors a lot of waste and other undesirable matter that even
regular vacuuming will not fully remove.
D. General Maintenance (Overall Tank Cleanliness)
In addition to consistently maintaining good water chemistry via your wc’s, you will need to incorporate some other
maintenance items in your daily, every second day, semi-weekly, or weekly routines. Wipe down the inside walls of your
tank when doing wc’s in order to remove algae and discus’ shedded slime coating, which film onto the glass. If your tank
is planted, you will need to regularly vacuum your substrate. Semi-weekly or weekly might be enough, but some do it
with each wc if not more frequently than that.
If you are using HOB filters, your filter media should be rinsed on a regular basis, no less than weekly, but better still,
semi-weekly. Rinse the filter media in the tank water after it has been pumped out, or in conditioned warm tap water, so
as to avoid destroying any significant amount of beneficial bacteria. If you were to concurrently rinse all, or most, of the
media in untreated tap water, for example, or discard most media items all at once for replacement with new, (such as
very dirty and deteriorating foam pads, sponges, filter floss, etc.) you would effectively be removing or destroying a very
large portion of your biological filtration system (the beneficial bacteria). This could result in dangerous spikes of
ammonia and nitrites. Change old, discard-ready media to new on a rotated basis, one filter at a time, and/or one media
component at a time. The use of pre-filters on your water intakes will improve the efficacy of your filters, whether HOB
If using canister filter(s), discus keepers will usually rinse media and clean their filters on a less frequent basis, on average
every second or third month. The use of pre-filters on their intakes, coupled with the size, power and efficiency of these
filters as opposed to HOB’s, will make this more extended cleansing routine adequate.
III. PURCHASING FISH
A. Ages, Sizes, and Appearance
If you’re thinking of growing out juveniles, or ‘juvies’, ideally you’ll want to acquire 8 cm (3”) size specimens which will
likely be about four months old. As a general guide, six to eight or even ten fish of this size will do well in a 220 L (55 gal.)
tank, at least until they approach maturity. At this point, you will do well to reduce the number to six or seven. Your
second option is to go for larger, older specimens, near adult or adult of 10 cm to 18 cm (4”-7”). You might like to see
them develop into at least one mated pairing, for breeding. In this case, you’ll need to limit the number to six or seven in
a 220 L (55 gal.) tank. As a novice to fish-keeping, you should think carefully before buying very small discus less than 5
cm long (2”) (fry). They require more frequent feedings and frequent large water changes, and they have a low tolerance
for poor water quality which generally leads to stunting.
Look for fish that have a round body (not oval or ‘football’-shaped), clear eyes, and a respiration rate with gill cover
movement that is fairly slow and steady. Their fins should normally be outstretched, not clamped, and they should be
eating well. The size of their eyes should appear to be in an attractive proportion to their body size. A stunted fish will
have unusually large eyes compared to the body, which will be somewhat evident.
When viewed head-on, the forehead, or brow should not appear pinched in, nor should the stomach/lower body area
below the head. In a solid colored fish, the coloration should be bright, not extremely pale and washed-out looking. Avoid
any discus that appear dark in color.
They should be active and appear comfortable with their surroundings, not darting about and/or hiding. They should not
shy away from the front of the tank as you view them. Ask your livestock source to feed them and then watch to ensure
they eat. Find out what they have been eating, how frequently, and the temperature and pH of the water they have been
kept in. Learn as much as you can of their background so that you are well-equipped to keep them yourself.
Figure 4 Pair of Adult Blue Diamonds
B. Sources of Livestock Purchases
Probably the most critically important element in successful discus-keeping is to buy your fish from a knowledgeable,
experienced, reputable and fully reliable source. This is almost your guarantee of getting great- looking, healthy fish.
There are, generally, three sources for discus:
- Local Breeders: They will usually provide healthy fish, acclimated to local conditions. You will first need to obtain
positive references to fully satisfy yourself that the breeder sells healthy, quality fish. This route does of course
support local breeders, but the fish being sold generally tend to be very young. Reputable breeders understand that
sales are often by word-of-mouth and so they want to maintain a positive reputation.
- Importers: Like the breeders, reputable importers strive to maintain a positive reputation. Again, get references.
This source generally costs more than local breeders, but the variety available is much better and the size bigger.
- LFS: This source is usually expensive. They are unwilling or unable to invest the time and money discus require. It
would probably be non-profitable if they did. The fish are often on a central water system, and so pick up illnesses
from other fish. The quality, even if healthy, tends to be poor. This source is not recommended.
While some LFS sell healthy, quality discus, most do not, so you would be well-advised to buy your fish from an
experienced long-term breeder or importer in or near your area. Many discus keepers acquire their stock from wellknown
sources of high quality discus, and have them air shipped to their location. If and when doing this, it is important
to ask for photos in advance of the fish you will be buying. The delivered product should equate to the photos you were
given. Do your homework here, and seriously consider getting your fish from one of several experienced and reputable
sponsors of the The British and International Discus Keepers Association (BIDKA), the Simply Discus, or other forums.
Check them out and make enquiries of other forum members.
C. Stocking Ratios
How many fish should you buy? Discus are social fish and have shown to be most comfortable when kept in a group of
five or more. They are generally peaceful, but being cichlids, they are prone to somewhat aggressive behavior toward
their own kind . They will almost always develop a “pecking order” – quite normal behavior for discus. While this
somewhat “bullying” behavior can be quite stressful to those being picked on, it is rarely physically harmful in a group of
this size. Discus rarely show aggression towards other fish. Keeping fewer fish than suggested above will often result in
one or two being bullied to an undesirable extent by the dominant one as the pecking order is established. So, there is
safety and security in numbers.
The generally accepted ‘rule of thumb’ is to keep no more than one adult fish per 40 L (10 gal.) of water, or five or six
adult fish in a 220 L (55 gal.) tank. If raising juvies, double the number of fish should do well in the same-sized tank until
they grow out to 10 cm (4”) and over. Then you will have to consider downsizing your group of fish, getting a larger tank
for them, or getting another tank and splitting the group.
Overstocking is never a good idea. It can be stressful on the fish, and it ties the hobbyist to his or her tank. One can’t miss
a wc, and one is completely dependent on a never-fail source of electricity.
D. Potential Tank Mates For Discus
There are a number of types of fish which are compatible with discus, and which are more or less tolerant of the higher
discus tank temperature. Avoid smaller fish which could become ‘lunch’ for discus, or fast-moving fish such as zebra
danios which can make them nervous. Some fish are “nippers” and are to be avoided, such as tiger barbs. Many fish
cannot tolerate discus temperatures.
Examples of generally good discus tank mates include some species of tetras such as Cardinals, Rummy-noses, Glowlights,
and Lemon tetras. Harlequin or Copper Rasboras and Hatchet fish are acceptable. Bushy-nosed Plecos and
German Blue Rams are also good tankmates. A number of bottom dwellers are good mates as well, such as sterbai,
peppered, bronze, or emerald Corydoras, to name a few. Dwarf or Pearl Gouramis should do fine as well, but not other
strains of Gouramis which may tend to be overly aggressive and stress the discus, or out compete them for food. A
number of discus hobbyists have successfully kept bettas and angelfish with discus.
Figure 5 Tank mates include Corydoras and Cardinal Tetras
IV. CARING FOR THE DISCUS
A. Acclimatizing the Fish
There are two commonly used methods for releasing newly-purchased fish into the home aquaria. One is often referred to
as ‘drop and plop’, where the discus are simply removed from the bag and placed in the tank without any further prep.
The following second method eases the transition.
Once you get your newly-purchased fish home, you should properly acclimatize them to the temperature and pH of your
tank water. This is a fairly simple procedure, taking no more than an hour or so from start to finish. This will limit stress
and shock caused by a large change in temperature or pH.
First, float the bag of fish in your tank for 20 minutes to equalize the bag water temperature to the water in your tank.
Then open the bag and check the pH in both your tank and the fish bag to satisfy yourself that there is no wide variance.
If the pH is approximately similar, the fish can be added without further acclimation.
If however, there is a variance of more than 0.3 or 0.4 in the pH, then begin to add water from your tank into the bag,
slowly and in small increments – 15% or so of the bag’s water volume each time, allowing five to ten minutes between
each addition, until you have approximately doubled the volume of water initially contained in the bag. Finally, do not
pour the water, with fish, directly into your tank, as the bag water will be polluted with fish waste. Gently pour the water
from the bag through a fish net into a bucket. As each fish slides into the net, pause your pouring and place the netted
fish into your tank.
As a slight alternative to this method, some hobbyists place the fish and bag water in a bucket or other container. Then,
using an air supply hose with a gang valve, water is rapidly dripped from the tank into the bucket to at least double the
volume over the course of about an hour. The fish are then netted out and placed in the tank.
B. Quarantining New Fish
If you bought your fish from a reliable source, your tank is cycled with no other fish in it, and you have acclimatized your
fish as above, then you may place your new fish directly into the tank.
If you already have fish in your tank, you need to quarantine the new ones. Quarantining means completely isolating the
new fish from all other fish, in a separate tank specifically set up for this purpose, and preferably located in a separate
room. Also, a heater, filter, hoses, bucket, thermometer, etc. should be set aside for use solely in the quarantine tank. Take
care that water on the hands from the quarantine tank does not get into the other tank, and vice versa.
You need to do this as the new fish may be harboring pathogens they are immune to, but the existing fish are not. Also,
the stress of the move may cause problems for the new fish, and you don’t want to transfer this to the existing tank.
Finally, if the existing discus harbor pathogens they are resistant to, but the new fish are not, then one risks the potential
loss of some new fish. Therefore, all new fish, whether purchased from the same source or not, should be quarantined.
A quarantine should be of four to six weeks duration. Then, take one fish from the main tank and one fish from the
quarantine tank, place them into a third tank and quarantine for a further two weeks. If there is only one fish in the
quarantine tank, the fish from the main tank can be added to the quarantine tank. This needs to be done in order to
minimize the impact to only one fish if a problem develops. If problems do arise, either the new fish or the existing fish
need to be treated.
Alternatively you may opt, as many hobbyists do, to use a single quarantine tank rather than two. Add one fish from
your main tank to the new stock of fishes and observe them during the quarantine period. This approach may prove
riskier, in that if your original fish have something they are resistant to, but the new fish are not, then you risk infecting
all of your new fish, rather than only one. If this were to occur during this method of quarantine you would need to treat
all of the fish, new and original. If the previous method had been followed, only the original fish and the two fish in the
third tank would need to be treated.
A tank in the 40 L to 120 L (10 gal. to 30 gal.) range will usually suffice as a suitable quarantine tank, keeping in mind the
number and size of the new fish being quarantined. Remember the ‘size of fish per litre’ rules. Before using it, this tank
should of course be cycled, filtered, and of the same temperature and pH as your main tank. This tank can also later
serve as a hospital tank for medicating sick fish.
C. Diet and Nutrition
Your discus need to be fed a varied, healthy diet which provides them with sources of protein, minerals and vitamins
essential to their health and development.
Packaged frozen foods are excellent sources of most of the essential elements. Some examples are blood worms, mysis
shrimp, krill, and brine shrimp, all of which are usually fortified with vitamins and minerals. Discus will usually, readily
take a variety of good quality flake foods and pellets. Many aquarists feed homemade foods to their discus, often using
recipes with beef heart. Some are heavy on protein, while others contain large percentages of vegetable matter. Four
good recipes may be found @ http://www.buzzle.com/articles/discu...od-recipe.html
Google’ing discus fish food recipes
will provide many links.
A general guide is that the younger the fish, the more frequent the feedings should be. A juvenile discus of 6 to 10 cm
(2.5”to 4”) should grow well with four to six feedings daily. Feed only small amounts each time, usually only as much as
your fish can consume in under five minutes. A 10 cm (4”) fish should be fed two to four times a day, and an adult discus,
once or twice daily.
Figure 6 Beautiful Healthy DIscus
V. HEALTH OF YOUR DISCUS
When quarantine procedures are not followed and cross-contamination occurs, or the fish are experiencing stress, they
can succumb to parasites, bacterial infections or funguses.
Causes of stress are many and varied, but the most common are:
- Poor water quality and conditions
- Poor diet
While most, if not all, discus harbor some form of parasites or other pathogens on or within their bodies (just as animals
and humans do), healthy discus’ immune systems are well able to deal with this, keeping matters in check and nontroubling.
When the immune system is weakened and starts to break down, pathogens get the upper hand, causing poor
A. Recognizing a Problem
If and when any of your fish ceases acting normally and begins to behave in strange, unusual ways, it’s almost always a
sign that something has begun to go wrong. Examples of strange behavior include isolating itself from the rest of the
group and hiding a good deal of the time. It may refuse to eat, face the rear of the tank, display clamped fins, show a lack
of color, or a very darkened color, or rub itself on plants or driftwood. All of these behaviors are signs of distress in the
B. How to Proceed
First, test your water for ammonia, nitrites, nitrates and pH. If your tests show any unusual abnormality, such as the
presence of ammonia or nitrites or a significant change, up or down, in your normal pH level, immediately do a large
water change. Check the pH of the wc water before you do the change, and then test your tank water again after the wc
to see what changes have taken place in either ammonia, nitrite, nitrate or pH levels.
There is no need to panic. Stay calm, observe the characteristics of your tank and all your fishes’ behavior, and begin
seeking the help of other forum members by posting a thread, detailing all of your tank conditions. Explain the problem,
outline the symptoms, which meds you have already tried and the results, and state the tank size, age, number and size of
fish, your wc regime, whether bare-bottom or other, temperature, pH, ammonia, nitrite, nitrate readings, and anything
new you have recently added to your tank.
You will get help from experienced discus keepers on the Simply Discus and BIDKA forums who will advise you on how
Forum links to Disease Questionnaire
This guide should have supplied you with all of the step-by-step instructions necessary to properly launch you into
successful discus keeping. The sections on cycling the tank, water conditioning, water changes, acclimatizing and
quarantining, along with sources of your livestock purchases, are particularly important. You would do well to review
them carefully, and ensure you have a good understanding of what you will need to do. If you have questions regarding
any matters related in this guide, you should of course not be shy about asking other fish forum members. The “search”
button can be very useful in finding information.
It is sincerely hoped that after reading this, you will have cemented your decision to move ahead with plans to keep
discus. If you make an honest effort to adhere to the principles set out in this guide, it is almost certain you will find that
the patience and dedication involved in discus-keeping will make for an extremely interesting and rewarding experience.
You will soon see for yourself that discus are not only beautiful, but have the unique personalities to match!
Have fun with the hobby!
Figure 7 Beautiful Show Aquarium.
Au, Dick - Trophy Discus (Cichlid Press 2007)
Au, Dick - Back to Nature Guide to Discus (Aqualog Verlag GmbH)
Soh, Andrew - Discus: The Naked Truth (Andrew Soh Pub., 2005)
Soh, Andrew – Discus: Problems and Solutions (Andrew Soh Pub., 2009)
Shulze, Eberhard – Discus Fish: The King of All Aquarium Fish (Discus Limited, 1988)
Additional Credit – Honorable Mention:
To Keith Perkins, for assistance and improvements to final text.