Keeping discus successfully does not require buying every aquarium product on the market. However, because discus prefer warm, clean, stable water, choosing dependable equipment can make their care much easier.
The most important discus fish supplies include a suitable aquarium, reliable filtration, accurate heaters, a thermometer, a water-testing kit, quality food, and basic water-change equipment. These essentials help you maintain the consistent conditions discus need without filling your cabinet with products you may never use.
I have kept and bred discus for many years, and one lesson I’ve learned is that expensive or complicated equipment cannot replace good aquarium maintenance. A simple, dependable setup combined with regular water changes and sensible feeding will usually serve you better than a collection of unnecessary chemicals and gadgets.
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Start With a Properly Sized Aquarium
Discus grow into tall, rounded fish and need adequate room to swim. Most adult discus average about 6 to 8 inches across, although their final size can vary. They also feel more secure when kept in a group. A practical formula I have used for many years is approximately one adult discus for every 10 gallons of aquarium water. This is a general stocking guideline, not a substitute for good filtration, regular water changes, and adequate open swimming space.
A 55-gallon aquarium is often treated as a practical starting point, but a larger tank gives adult discus more swimming room and provides greater water volume. More water generally changes temperature and water chemistry less quickly than a small amount of water, making a larger aquarium easier to keep stable.
The aquarium’s shape is also important. Discus are tall fish, so a tank with good height and a reasonable front-to-back depth is more suitable than a long but very shallow aquarium.
Avoid overcrowding. Too many fish in a limited space create more waste, increase competition at feeding time, and make maintaining water quality more difficult. The aquarium must also provide enough open swimming space rather than being completely filled with decorations.
Dependable Aquarium Filtration
Good filtration is one of the most important investments you can make for a discus aquarium. The filter must handle biological waste, trap debris, and circulate the water without creating an excessively strong current.
Canister filters are popular for discus aquariums because they hold a generous amount of mechanical and biological filter media. They can provide strong filtration while returning the water through a spray bar or adjustable outlet that helps distribute the flow.
One possible choice for a larger discus aquarium is a Fluval 407 canister filter. It is intended for aquariums in the 50-to-100-gallon range, although the actual filter needed depends on the aquarium’s stocking level and maintenance routine.
A hang-on-back filter can also work, especially on a smaller tank or as additional filtration. Sponge filters are useful because they provide biological filtration and gentle water movement. They can serve as the main filter in lightly stocked or frequently maintained setups, or as backup filtration in a larger aquarium.
Whatever filter you choose, do not replace all the established filter media at once. The beneficial bacteria living on that media help process ammonia and nitrite. Rinse reusable media gently in removed aquarium water when needed rather than cleaning everything under untreated tap water.
The goal is not simply powerful filtration. You want dependable filtration without creating a strong current that forces the discus to struggle. In many cases, I personally prefer sponge filters for discus aquariums up to 55 gallons, provided the tank is not overcrowded and regular water changes are performed. In my discus breeding tanks, I use only sponge filters because they provide gentle water movement, dependable biological filtration, and are safe around eggs and newly hatched fry.
Reliable Aquarium Heaters
Discus require warmer water than many ordinary community fish. Aquarium-raised adults are commonly maintained at approximately 82°F to 86°F, depending on their age, health, tank mates, and the conditions in which they were raised.
A reliable adjustable heater is therefore essential. Choose the heater size according to the aquarium’s water volume, the normal room temperature, and the manufacturer’s directions.
For a larger discus aquarium, I prefer using two appropriately sized heaters instead of relying entirely on one large heater. Two heaters placed apart can distribute heat more evenly and provide some protection if one stops working. They should still be checked regularly because any heater can eventually fail.
An adjustable EHEIM aquarium heater is one dependable option. The exact wattage must match your aquarium rather than being selected only by brand name.
Always unplug a heater before draining water below it. Allow it to cool before exposing it to air, and follow the manufacturer’s instructions when placing it back into operation.
An Accurate Aquarium Thermometer
Never depend only on the numbers printed on the heater’s adjustment dial. Use a separate aquarium thermometer to confirm the actual water temperature.
Place the thermometer where it gives you a useful reading. It should not be directly beside the heater, where the surrounding water may be temporarily warmer than the rest of the aquarium.
Check the temperature every day. It takes only a few seconds and may help you notice a problem before the fish become seriously stressed.
A Freshwater Water-Testing Kit
Clear aquarium water is not necessarily safe aquarium water. Ammonia, nitrite, nitrate, and pH cannot be judged accurately by looking at the tank.
The API Freshwater Master Test Kit measures pH, high-range pH, ammonia, nitrite, and nitrate. These are useful measurements when cycling an aquarium, investigating a problem, and monitoring regular conditions.
In a properly cycled discus aquarium, ammonia and nitrite should remain at zero. I recommend keeping nitrate at no more than 20 ppm. If it is around 20 ppm, keep a close eye on it and use regular partial water changes, sensible feeding, proper stocking, and filter maintenance to prevent it from rising.
The exact pH is often less important than maintaining stable conditions suitable for the fish you own. Many domestically raised discus can live successfully in moderately hard water with a higher pH. Repeatedly adding chemicals to force the pH up or down can create harmful fluctuations.
If you want more information about your source water, separate tests for general hardness, carbonate hardness, and total dissolved solids can be useful. They are not always necessary for someone keeping ordinary aquarium-raised adult discus, but they can help explain differences between tap water and aquarium water.
Water Conditioner for Tap Water
If you use municipal tap water, you need a dependable water conditioner that treats chlorine or chloramine before the new water reaches your fish.
Follow the label directions carefully. Adding more conditioner than necessary does not make routine water changes better. The replacement water should also be reasonably close to the aquarium’s temperature to avoid suddenly chilling or overheating the discus.
Buy a conditioner in a size appropriate for the amount of water you normally change. Highly concentrated products may appear more expensive at first but can treat considerably more water per bottle.
Always keep the water conditioner with your water-change equipment so you do not forget it. Untreated tap water containing chlorine or chloramine can quickly harm or kill fish and damage the beneficial bacteria in the aquarium. I have heard too many horror stories from people who completed a water change and forgot to add conditioner. Make adding it a required part of every water change. If you are unsure whether you added it, follow the product directions; personally, I have never harmed my fish by accidentally adding an extra dose or two. I would rather accidentally add a little extra than forget it completely. lol – Personally, I’ve always used Seachem Prime water conditioner.
Water-Change and Cleaning Equipment
Regular partial water changes are a major part of discus care. Fortunately, the required equipment is simple.
A gravel vacuum or aquarium siphon allows you to remove water while collecting uneaten food and debris from the bottom. If the aquarium is close to a suitable faucet and drain, a faucet-connected water-change system may reduce the need to carry heavy buckets.
Use aquarium equipment only for the aquarium. Buckets, hoses, sponges, and other tools should never come into contact with soap, household cleaners, pesticides, or other chemicals.
A bare-bottom discus aquarium is easy to siphon because waste remains visible. A decorated aquarium with sand or gravel can also be successful, but the substrate must be cleaned carefully enough to prevent debris from accumulating.
How much water you change and how often will depend on the number and size of the fish, feeding schedule, filtration, aquarium volume, and nitrate level. However, I recommend performing a partial water change at least once a week. Growing discus that receive several meals per day usually require larger or more frequent water changes than lightly stocked adult display fish. I have been addicted to keeping discus since the 1970s, and for many years I performed a 50% water change every day. Back then, it was what I called the “bucket brigade”—until I finally graduated to an aquarium water-change system that made the job much easier.
Quality Discus Food
Discus benefit from a varied, nutritious diet. They do not need to be fed only live food or homemade mixtures.
A quality flake food that I personally recommend is Ocean Nutrition Prime Reef Flakes. It is suitable for both marine and freshwater fish, and I have fed it successfully to discus. It contains 53.4% crude protein, which helps support healthy growth and good body condition. I recommend using it as part of a varied diet rather than feeding only one type of food.
I have fed prepared frozen beef heart, frozen brine shrimp, and other suitable frozen foods to add variety to my discus’ diet. Feed sensible portions and remove any uneaten food because it can quickly foul the water. Always buy frozen or live foods from a reliable aquarium supplier to reduce the risk of contamination.
For smaller discus, I have used a small handheld kitchen grater to shave the prepared frozen beef heart into smaller pieces. This makes it easier for young or smaller fish to eat. Only grate the amount needed for that feeding, and remove any uneaten food before it affects the water quality.
Feed only what the fish will consume within a reasonable time. Discus can be slow and deliberate eaters, so watch the entire group. Make sure shy fish receive food and that dominant fish are not taking everything.
Remove uneaten food before it begins to decay. Overfeeding wastes money and places unnecessary pressure on the filter.
Air Pump and Sponge Filter
An air pump is not always required in every aquarium, but it is useful to have one available. Warm water holds less dissolved oxygen than cooler water, so good surface movement is important in a warm discus tank.
An air-driven sponge filter provides gentle circulation, additional biological filtration, and surface movement. It can also remain ready for use in a quarantine or hospital aquarium.
Choose an air pump rated for the aquarium size, and install a check valve in the airline when the pump sits below the water level. The check valve helps prevent aquarium water from flowing backward during a power failure.
Battery-powered air pumps are also worth considering for emergencies, especially in areas where power outages occur.
A Separate Quarantine Setup
A basic quarantine aquarium can protect every fish already in your main display. It does not need to be elaborate.
A quarantine setup can include a simple tank, lid, adjustable heater, thermometer, seasoned sponge filter, and a few easy-to-clean hiding places. Keeping the bottom bare makes it easier to observe waste and monitor whether a new fish is eating.
New fish may look healthy at the store but develop symptoms after the stress of transportation. A separate tank gives you time to observe them without exposing the established aquarium.
A quarantine tank is also useful when a fish becomes ill or injured. Treating one fish separately can be safer and less expensive than medicating an entire display aquarium.
Supplies You May Not Need
Aquarium stores sell many products that promise clearer water, perfect pH, instant solutions, or dramatic improvements. Some have legitimate uses, but they should not be added automatically.
Avoid purchasing several medications “just in case” and then treating fish without identifying the likely problem. Unnecessary medication can stress fish, affect the biological filter, and make the real issue harder to recognize.
You also do not need to change the pH constantly unless there is a specific reason. Stable, clean water is generally safer than a supposedly perfect number that rises and falls after every chemical adjustment.
Carbon dioxide systems, powerful plant lighting, ultraviolet sterilizers, automatic dosing equipment, and electronic controllers may be useful in certain aquariums, but they are not essential discus fish supplies for every keeper.
What You Really Need for Discus
The basic list is straightforward:
- An appropriately sized aquarium
- Dependable filtration
- Reliable adjustable heaters
- A separate thermometer
- A freshwater test kit
- Water conditioner
- Water-change and cleaning equipment
- Nutritious discus food
- An air pump or sponge filter
- A simple quarantine setup
Buy the best dependable equipment your budget allows, but remember that no product can maintain the aquarium for you. The filter still needs attention, the water must still be tested, and regular partial water changes remain necessary.
Discus are often described as impossibly difficult fish. They do require consistency, but their needs are not mysterious. Provide warm, stable water, good filtration, proper food, adequate space, and regular maintenance, and you will have the foundation of a healthy discus aquarium.
The right discus fish supplies make that routine easier. More importantly, they allow you to spend less time struggling with preventable problems and more time enjoying these beautiful, intelligent fish.
