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Discus 101: How to Raise Juvenile Discus by Willie Loh

People are attracted to discus because they are regarded as the most beautiful fish in the freshwater aquarium.  Herbert Axelrod crowned discus as King of the Aquarium, a term which is commonly cited in aquarium books.  While his hyperbole may have been driven by marketing concerns, the title is widely accepted for Symphysodon species.

For whatever reason one may be tempted to try discus, there exists a tremendous body of literature on raising and breeding this fish.  I like to share my experiences of the past five years with this fish.  My experiences reflect an advanced hobbyist who became enamored, then obsessed, with discus.  This is not a primer on raising discus.  The specialized texts offer far more detail than I can provide.  I will focus on areas where my experiences diverge from standard texts on discus.

This is the first of three articles on raising and breeding discus.  This one will deal with a variety of issues related to raising discus.  Articles will follow on breeding and buying discus. 

Raising Discus

Most general aquarium books include a section on discus.  The information presented is usually so perfunctory as to be useless, but it allows the publisher to add nice discus pictures, often on the front cover.  Many books indicate that these fish are more appropriate to advanced aquarists.  In contrast, every discus specialty text I have read emphasizes that these fish are NOT hard to raise.  Of course, such specialty books are always written by discus experts. 

In my opinion, discus is much harder to raise than most aquarium fish.  Beginners are going to have a difficult time with discus, but an experienced aquarist who understands their requirements should expect success. 

There’s no getting around the fact that these are finicky fish.  Without optimum conditions, discus will rapidly go into an irreversible decline.  When this happens, the beginner compounds the problem by trying to adjust water chemistry or adding medication.  At that point, the rest of the tank usually goes into decline.  When tetras die, the aquarist pays a nominal sum to learn from his mistakes.  When discus die, he/she can be losing $25 per fish. 

What do discus need?  They need very clean water and they need it all the time.  Discus evolved in very acidic water where microbial populations are low.  They are extremely susceptible to dirty conditions.  So the solution is quite simple, make regular water changes.  How much?  As much as you can.  How often?  See previous answer.

Willie can do 100% water changes by using aged water of the same
temperature and parameters as that removed from the tank.

I make 100% water changes weekly and many breeders do more.  What would be optimal?  In my opinion, a 15% - 20% water change daily would be absolutely fantastic.  However, I have a job and a family so this water change schedule is my compromise.  But that’s not enough.  Discus produce slime on their body.  This slime is shed constantly and coats the inner surface of the tank to promote bacterial growth.  I try to wipe down every discus tank every other week.  Others breeders wipe down their tank weekly. 

Discus also prefer soft water, but this preference is far less important than cleanliness.  In fact, achieving optimal conditions is far less important than maintaining constant water conditions.  Unless your faucet puts out liquid rock, focus on making regular and large water changes.  Discus will adapt to most conditions, including pH up to 7.8 and 350 ppm microsimens of hardness.  However, they cannot survive in dirty water or constantly changing water conditions. 

Actually, no fish can adapt to constantly changing water conditions.  However, very few fish have this requirement for clean water.  I recommend against fiddling with water chemistry because it’s very hard to do so and still make frequent water changes.  If your conditions are worse than described above, put a peat filter in line and keep the water changes coming. 

Because the hygiene requirement is so high, most aquarists keep discus in bare bottom tanks.  My tanks typically have a sponge filter and a heater.  An outside filter may be added to large tanks to increase aeration and biological filtration.  The heater sits on the bottom of the tank so that I can make large water changes without meltdowns. 

Will large water changes stress discus?  They will if water conditions change.  Large water changes do not create stress if the tank water is relatively clean.  Do not make large water changes if the tank has been neglected.  Start with small, frequent changes and work your way up.  Vacuum the bottom of the tank during water changes, even if the tank contains gravel and plants. 

Can discus be kept in heavily planted tanks?  Of course they can, but water changes and regular wipe downs are still required.  Will they grow as well in planted tanks with gravel?  They can, but it will take a lot more work.  The gravel absolutely has to be vacuumed weekly.  Can they coexist with other tank mates?  Yes, but these fish better get used to large water changes.  Both fish and plants also have to get used to high temperatures, i.e. 84F or higher.  Only a few Corydoras species, for example, can survive these conditions.  Angelfish should be avoided as tank mates as both species share similar disease susceptibilities. 

Willie grows out his discus in bare bottom tanks.

Some discus purists become offended at the very suggestion of raising discus in a community tank, even raising them in a species tank with plants.  My views are not so radical, but we have to understand the inherent compromises of a show tank.  No matter how well they are cleaned, these tanks are going to be much dirtier than bare bottom ones.  Its impossible to do a good wipe down on a planted tank since the gravel also accumulates slime.  Many high protein foods will foul the water and are difficult to use in these tanks.  If you would like to have beautiful discus in a heavily planted tank, I recommend getting adult fish. 

Does turbulence from power filters disturb discus?  This question reflects a lack of experience with this species.  Because large and frequent water changes are necessary, the type of filter used is unimportant.  Canister and wet/dry filters are usually unnecessary.  Mechanical and chemical filtrations are less important because the tank should always be clean.  Underground filters, which are very effective for biological filtration, are not recommended because they accumulate mulm, which can be difficult to remove.  For optimal hygiene, most aquarists use sponge filters that can be squeezed out and cleaned weekly.  Biowheels are also popular for their biological filtration capacity.  

A high quality diet is important to produce high quality discus.  These are large fish and require high levels of protein in the diet.  Mature discus should grow to at least 4" from head to tail.  In my experience, discus will eat almost anything.  My fish are fed flake food in the mornings and afternoons.  They also get beef heart, frozen bloodworms and/or live red wriggler worms every day.  The feeding schedule ranges from 8 times a day for 1-month-old juveniles to twice a day for breeders.  Automatic feeders are strongly recommended for raising young fish.  In Asia, live food is typically used and discus in grow out tanks are fed constantly. 

The Internet is full of websites filled with incredibly complex beef heart recipes, which incorporate shrimp, fish, flakes, Spirulina powder, vitamins, garlic, etc.  I prepare 100% beef heart because complex recipes are difficult to prepare and food safety is always a concern with ground meat.  All the other foods are fed separately, to simplify food preparation and provide some diversion for the fish. 

Tremendous controversy exists with feeding live food.  Tubifex worms have been implicated in a variety of discus epidemics.  Many books also warn against black worms.  Although I do not use either in my tanks, not all black worms are problematic.  It is certainly possible to obtain clean sources of black worms, but its up to the aquarist to ascertain the source.  Food scientists will tell you that freeze dried and frozen worms cannot transmit disease, despite all the warnings on the Internet.  To avoid any possibility of introducing disease, I supplement their diet with red wriggler worms and white worms from my own cultures. 

Because these are potentially large fish that require clean water, adult discus should have plenty of room – 10 gallons/fish.  However, juvenile discus should not be kept in overly large tanks.  These are social fish and will become very skittish in large tanks.  Six 1.5" discus can grow very well in a 29-gallon tank.  They will do better in large tanks when they get to 2.5". 

In summary, raising discus is not difficult as long as they are provided with constant water changes and strict tank hygiene.  Beginners fail because they ignore these absolute requirements and see these expensive fish last only 3 - 4 months in their community tanks.  The experienced aquarists understand the time commitment and maintain this regimen to see those 1" juvenile fish grow into spectacular specimens befitting the title of the “King of the Aquarium”.