Discus
Fish
The king of the aquarium, and it knows exactly how good it looks!
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🤓 Did you know? Newly hatched discus fry feed on a nutrient-rich mucus secreted from both parents' skin, most intensively for roughly the first two weeks after they become free-swimming, with a gradual weaning over the following two weeks. It is one of the only documented cases of sustained direct parental feeding in fish, and a 2010 study found the mucus carries immune antibodies and protein at levels that rise and fall across the feeding period, in a pattern the researchers compared to mammalian milk.
🗓️ The first week
The numbers a new owner needs in the first week, each from the article it links to. Rows with no link come from the encyclopedia.
- Tank size
- 55 gallons is the entry point and a floor, not a target; experienced keepers recommend 75 or larger, since a 55 forces far more frequent water changes for a proper group. Taller and deeper over long and shallow.Setup guide →
- How many
- 5 to 6 or more. Three gives the bottom fish nothing but the bottom; six spreads the pecking order thin. The dark fish hanging at the surface in a corner is the one to act on, and the answer is more fish or more tank.Setup guide →
- Temperature
- 82 to 86°F, warmer than nearly every community fish, which is what limits tankmates. Many keepers run two heaters, since a heater failure at this temperature is a bigger problem.Setup guide →
- Water chemistry
- Soft and slightly acidic, roughly pH 6.0 to 7.0. Hard tap water usually needs an RO or RO/DI unit to get there, and that unit belongs in the budget.Setup guide →
- Water changes
- The routine that defines a working discus tank: weekly changes of 25 to 50%, and some serious keepers change every 2 to 3 days.Setup guide →
- Filtration
- A canister sized well above the tank volume is the common choice. A canister competes with the fish for oxygen and fails badly in an outage, so pair it with surface agitation or use a hang-on-back. No under-gravel filters.Setup guide →
- Put the tank somewhere quiet
- Nervous fish. A low-traffic wall, approached from the side rather than above, a background on the rear glass, and feeding at the same times each day.Enrichment guide →
- Structure and open water
- Tall stems and upright driftwood to orient to and break sight lines, with open water left to cruise in.Enrichment guide →
- Feeding schedule
- Adults 2 to 3 times a day, small amounts cleared within a few minutes. A short gut suits frequent small meals over one large one.Feeding guide →
- Diet
- A discus-formulated pellet or granule sized for a small mouth, with frozen or live bloodworms and brine shrimp regularly. Beef-heart mix as a supplement, not the staple.Feeding guide →
- Acclimation
- The default is a slow drip of 60 to 90 minutes. One discus breeder argues for a fast temperature and pH match instead, since oxygen depletes in the shipping water. Either way: lights off, and no food on day one.Handling guide →
- Tankmates
- Cardinal tetras, rummynose tetras, Sterbai cories and bristlenose plecos are the ones named consistently. Neons are disputed at 82 to 86°F, so cardinals are the safer warm-water tetra.Handling guide →
- Sexing
- Difficult outside of breeding. Raise a group and let pairs reveal themselves.Handling guide →
- Budget
- $20 to $40 for young common-strain fish, so a group of 5 to 6 starts at $150 to $250 even at the budget end; premium strains reach $200 to $450 a fish. Setup roughly $600 to $800, then $20 to $50 a month.Cost guide →
- Lifespan
- 10 to 15 years with stable care; some sources put typical closer to 8 to 10.Cost guide →
- Adult size
- 6 to 8 inches (15 to 20 cm) in diameter.
- Quarantine
- A bare hospital tank with its own net and siphon, never shared with the display. A sponge filter gives gentle biological filtration.Quarantine guide →
- Power outage
- Oxygen is the threat, not darkness. Unplug the filter rather than letting it sit dead in the water, and keep the surface moving.Power outage guide →
🚨 Emergency card
Test the water first, then act on these today. Aquatic vets are rare, so nearly all of this is handled at home.
- Small white spots on skin and gills after flashing against decor, weakness, appetite loss
- Pitting, small holes, and erosion around the head and along the lateral line
- Labored or rapid breathing, flashing, excess mucus, sometimes spots on the body
- Ragged, receding fins with discolored edges, cloudy eyes, or abdominal swelling
Ich treatment for discus runs hotter than the standard advice, toward roughly 90°F rather than the 82 to 86°F they already live at.
📰 Where to go next
How Much Does Discus Ownership Really Cost?
$20 to $450 a fish by strain, $600 to $800 for the tank around them, and why the fish is rarely the biggest line.
Discus Tank Setup: Why the Water-Change Routine Matters More Than the Gallon Number
55 gallons as a floor and 75 as the real answer, 82 to 86F, and the water-change routine that defines the tank.
Discus Feeding: Schedule, Diet, and the Beef-Heart Debate
Two to three small meals for a short gut, the small-mouth sizing issue, and the peer-reviewed truth about discus milk.
Discus Aren't Handled, But They Are Surprisingly Social for a Cichlid
Why the acclimation advice genuinely splits, the narrow tankmate list, and sexing that mostly cannot be done by eye.
Common Discus Health Issues (And What Actually Prevents Them)
Ich at 90F rather than 86, flukes, and the hole-in-the-head study that undercuts the usual beef-heart explanation.
Discus Enrichment: A Nervous Cichlid Needs a Group and a Quiet Room
Why six is the number, the singled-out fish to watch for, and the free enrichment decision nobody mentions.
🛒 What to buy
Prices and the reasoning behind each item are in How Much Does Discus Ownership Really Cost?.
❓ Frequently Asked Questions
What size tank does a discus need?
55 gallons is commonly cited as the practical minimum for a small group, though several experienced sources push that to 75 gallons or more, since a 55-gallon tank forces noticeably more frequent water changes to keep pace with this species' bioload. Taller tanks are preferred over long, low ones given this fish's body shape.
What temperature do discus need?
82 to 86°F, warmer than nearly every other common community fish, warm enough that it narrows the tankmate list. Wild Heckel discus take water closer to 90°F, but 82 to 86°F is the standard target for captive-bred fish.
How often should I feed my discus?
Adults 2 to 3 times a day, in small amounts they clear within a few minutes, rather than one large daily meal. Discus have a short gut for their body size, and smaller, more frequent meals suit that digestive setup better than a single big feeding.
📚 Encyclopedia
Discus
Symphysodon spp.
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📰 Deep Dive
🐠 How Much Does Discus Ownership Really Cost?
🐠 Discus Aren't Handled, But They Are Surprisingly Social for a Cichlid
🐠 Common Discus Health Issues (And What Actually Prevents Them)
🐠 Discus Tank Setup: Why the Water-Change Routine Matters More Than the Gallon Number
🐠 Discus Feeding: Schedule, Diet, and the Beef-Heart Debate
🐠 Discus Enrichment: A Nervous Cichlid Needs a Group and a Quiet Room
🩺 Health and More
🐠 Aquarium Power Outages, Transport, and Moving Your Fish: The Complete Plan
🦠 How to Cycle a Fish Tank, Start to Finish: Fishless and Fish-In
🧽 Aquarium Filtration: How It Actually Works and How to Maintain It
🪣 Aquarium Water Changes: How Much, How Often, and What the Number Is For
🐟 Aquarium Stocking and Tankmates: How Many Fish, and Which Ones Go Together
🧪 Freshwater pH, GH, and KH: Why Chasing a Number Backfires
🤩 Fun Facts
🐠 Nursing Without Milk
Discus fry don't just hide near their parents, they feed directly off them. Both parents secrete a nutrient-rich mucus from their skin that fry bite at for minutes at a time, and a 2010 study found the mucus's protein levels rise and fall across the feeding period in a pattern the researchers compared to hormonally regulated mammalian milk. It's one of the only documented cases of sustained parental feeding in fish.