The number of discus you can safely keep together is a very common question I receive from many discus keepers.
If you search online you will see many conflicting responses.
The answer is not that easy. There are many factors to consider before being able to answer the question.
In this article I will explain all the different factors involved to help you decide how many discus is best for your aquarium.
The rule of thumb for how many discus you can keep together doesn’t necessarily apply to everyone but is 1 discus for every 10 gallons of water. Therefore if you follow that rule you can only keep 10 full size discus in a 100 gallon tank. I have been keeping discus for well over 25 years and have never followed this rule. My personal opinion is that 10 fish in a 100 gallon tank will make the tank look empty unless you plan on having a lot of plants and decorations.
What size is your tank? Obviously the bigger the tank the more fish you can keep. However make sure you take into consideration the amount of plants and decorations you have in your tank. Remember that they take up space therefore reducing the total water volume.
How much filtration do you have? As you know these fish require very clean water conditions. The more filtration you have the better. Keep in mind that every fish produces waste. The more fish you add the more waste that will be produced. Therefore you must make sure that you have sufficient filtration.
What kind of substrate will you have at the bottom of your tank? There are many options to choose from such as gravel, sand, or even nothing at all just a bare bottom. If you use gravel uneaten food and fish waste can get trapped between the pebbles. Your filter will not be able to pick it up so that will require you to perform more frequent water changes.
Are you keeping other fish with the discus? if so what kind are they? How big will they grow?
What size discus do you plan on keeping? Do you plan on starting with small discus and growing them out? If so, make sure you do not overcrowd the tank.
The discus pecking order. You must have at least 7 or more to help prevent bullying.
How much free time does your lifestyle/schedule allow for you to dedicate to discus tank maintenance?
What is your ultimate goal with keeping discus? Do you just want a show tank or do you plan on breeding and selling fish in the future?
At this point you are probably thinking “so how many discus can I keep? I’m still confused”
Here is my personal opinion which has worked well for me for over 25 years:
Allow 7 gallons of water for every discus fish. This will give the fish enough room to grow, swim and be happy. Do not crowd your tank with many decorations. Live plants are good if you want to go that route. Live plants actually help keep the water extremely clean. However plastic plants are fine also. Just make sure you clean then in warm water when they get dirty. It is extremely important that you keep up with your water changes (at least 30% per week of water changed weekly). The more water changes you do the faster your discus will grow.
I hope that you now have a better understanding of how many discus you can keep.
Feel free to contact me should you have any questions.