Discus are the undisputed kings of the freshwater hobby. Combining these vibrant, majestic cichlids with a lush planted aquascape is considered by many to be the absolute pinnacle of freshwater aquascaping. However, building a planted Discus tank is a massive challenge. You must balance the heavy bioload of large fish with the high temperatures they require—temperatures that will easily melt delicate aquatic plants if you aren't careful.
Sizing the Royal Court
Discus are schooling fish that grow up to 6 or 7 inches across. They need vertical swimming space and massive water volume to dilute their waste. A 75-gallon tank is the absolute bare minimum for a small school, but a 120-gallon or larger is highly recommended. If you are ordering a custom large-scale display, ensure the glass panels can handle the immense pressure with our Glass Thickness Calculator. Before you start filling it, calculate the monumental weight of that water and hardscape using our Volume & Weight Calculator to make sure your floor can actually support it.
Substrate: The Cleanliness Factor
Because Discus require heavy daily feedings (often beef heart mixes), keeping the substrate clean is mandatory to prevent bacterial infections. Many keepers opt for a shallow foreground of white pool filter sand so waste sits on top and is easily siphoned. In the background where you intend to grow large Amazon Swords, you'll need a deep bed of active soil.
To perfectly divide your sand and soil zones without buying excess bags of expensive substrate, run your specific layout dimensions through our Substrate Calculator.
Heavy-Duty Filtration
Large cichlids mean massive bioloads. You need heavy mechanical and biological filtration, but Discus are naturally slow-moving fish that hate being blasted by intense currents. The goal is high turnover with gentle, dispersed flow. A large canister filter outfitted with a spray bar is ideal. Find the perfect balance for your massive tank volume using our Flow Rate Calculator.
Lighting a Deep Tank
Discus tanks are usually 24 inches deep or more, which makes reaching the substrate with adequate PAR a challenge. However, Discus do not like blindingly bright lights. You need a highly penetrative LED fixture that can be dimmed or raised to create shaded zones. Dial in the perfect intensity for deep water penetration without stressing your fish using our Lighting Calculator.
Heating: The High-Temp Requirement
This is where most planted Discus tanks fail. Discus require incredibly warm water, typically between 82°F and 86°F (28°C - 30°C). Maintaining this temperature in a 100+ gallon glass box requires serious wattage. A failing heater in a Discus tank is a multi-thousand-dollar disaster. Determine the exact wattage required to safely hold these high temperatures using our Heater Calculator.
Best High-Temp Plants for Discus
Most popular stem plants will literally melt at 86°F. You must select plants that thrive in extreme tropical heat.
- Echinodorus (Amazon Swords): The quintessential Discus plant. They tolerate the heat perfectly and provide large, broad leaves for the fish to swim through.
- Vallisneria: Creates beautiful, tall jungle backgrounds that can handle the warm water.
- Epiphytes: Anubias Barteri and various Java Ferns can survive the heat as long as the water is well-oxygenated.
- Tiger Lotus: A stunning red bulb plant that absolutely loves high temperatures and provides excellent surface shade.
Frequently Asked Questions
Can I use CO2 injection in a Discus tank?
Yes, but with extreme caution. Warm water holds significantly less dissolved oxygen than cool water. Injecting CO2 further displaces oxygen, which can quickly suffocate large fish like Discus. If you run CO2, you must aggressively agitate the surface with a spray bar or airstone to keep O2 levels high.
How often should I change the water?
In a bare-bottom Discus breeding tank, keepers change water daily. In a heavily planted, established display tank with a mature biological filter, you can usually scale back to two 30% to 50% water changes a week, depending on your feeding schedule and bioload.
What are the best tank mates for Discus?
You need fish that can handle the 82°F+ heat and won't nip at the Discus' fins. Cardinal Tetras, Rummy Nose Tetras, Sterbai Corydoras (other Corydoras cannot handle the heat), and German Blue Rams make excellent companions.