Discus Fish Care Guide: Symphysodon spp. for UK Aquarists

After 15 years of keeping tropical fish and more than a decade specifically with discus (Symphysodon spp.), I can tell you honestly: these are the fish everyone wants after mastering a community tank, and they are also the fish that humble you the most when you get it wrong. If you are searching for discus fish because you have seen them in a mature planted aquarium and thought "that is what I want my tank to look like" — I understand completely. That was me in 2011. This guide is everything I wish I had known before I bought my first group.

This guide draws on data from FishBase^[1], the detailed species profile on Seriously Fish^[2], and peer-reviewed work on Symphysodon taxonomy and colour variation^[3]. Every care parameter here is sourced and cross-referenced with my own notes from running discus-dedicated tanks in UK hard-water conditions. Where I give an opinion, I will tell you it is one.

We currently stock discus in several varieties and sizes — browse our discus range to see what is available for heated tracked UK delivery.

Are discus hard to keep? An honest answer

Yes. I have to start here because so many online guides soften the truth. Discus are genuinely advanced fish, and selling them as "moderate difficulty" is how people end up watching expensive fish die in undersized tanks.

What makes them hard is the combination of demands. Warm water (28-30 C) cuts your compatible species list by 80%. Soft acidic water means RO water for most UK households. The workload is real — I do two large water changes per week on my own discus tank, more when there are juveniles growing out. And they are expensive, so mistakes hurt financially as well as emotionally.

The good news: if you have kept a stable community tank for a year, understand the nitrogen cycle properly, and are willing to commit to the maintenance routine, you can absolutely succeed. Modern German-bred Stendker discus are hardier than wild-caught fish from 30 years ago. The pathway exists. Just go in with open eyes.

Where discus fish come from

Wild discus inhabit slow-moving blackwater and clearwater tributaries of the Amazon Basin across Brazil, Peru, and Colombia^[1]. These are shaded forest streams choked with submerged wood, root tangles, and leaf litter, where the water is warm (28-30 C year-round), soft (often under 2 dGH), acidic (pH 5.5-6.8), and stained tea-brown with tannins^[2].

Understanding this habitat explains every part of discus care. They want warmth, dim shaded areas, vertical structures to orient around, gentle flow, and stable soft water. A brightly lit bare tank with strong current is the opposite of what they evolved for, and you will see that reflected in their colour, feeding response, and confidence within a week of moving them into the right environment.

In the wild they feed on small crustaceans, insect larvae, plant matter, and detritus^[1]. They are adapted to grazing on small particles in calm water rather than chasing fast-moving prey.

Discus varieties — what to actually buy

The discus you find in UK shops today fall into several distinct lineages, and understanding them changes what you should pay and what care level you are signing up for.

Wild-caught discus

Genuine wild Symphysodon are occasionally imported from Manaus and Tefé in Brazil. They are stunning, expensive (often 200 GBP+ per fish), and demand extremely soft acidic water. Recommended only for dedicated breeders. Avoid as a first discus.

German Stendker discus

Bred for decades by the Stendker family in Germany on a strict protein diet and adapted to tap water hardness. These are the hardiest domestic discus on the UK market and the right choice for most serious hobbyists starting out. Expect to pay 40-80 GBP per juvenile and 100+ for larger fish.

Malaysian and Asian farm discus

Bulk-bred in South East Asia with emphasis on bright colour and low production cost. Quality varies enormously — some are excellent, others arrive stressed, parasitised, or with stunted growth. If you buy Asian-farmed discus, buy them from a UK dealer who has held them for at least 4 weeks and observed feeding and behaviour.

Popular colour strains

• Turquoise — classic blue-green with dark horizontal bars
• Red Turquoise — intensified red overlays on turquoise base
• Pigeon Blood — bright peach-red with small black peppering
• Leopard — dense round spots across the body
• Red Marlboro — solid deep red, often with peppering
• Snakeskin — fine maze-like line patterning
• Blue Diamond — solid metallic blue, no bars
• Red Alenquer — richly coloured warm red variety

Wild-type patterning and newer designer lines appear regularly. What matters for your buying decision is body shape (round, not elongated), clear eyes, open fins, and eager feeding — not the flashiest colour in the tank.

Tank setup

Size and layout

250 litres is the minimum, and I would honestly push anyone asking to 300 litres or more. A 450-litre tank with a 150 cm footprint and 60 cm depth is the gold-standard setup — it gives you water volume stability, vertical swimming space for tall-bodied adults, and room for a proper group of 6-8 fish with sensible tank mates.

Height matters for discus more than for most species. Their deep circular body shape wants vertical swimming room; a tank shorter than 50 cm front-to-top looks cramped once adults are present.

Stocking suggestions for serious discus tanks

The rule of thumb I use is 40-50 litres per adult discus, plus headroom for companions. A group of 6 adults wants 250-300 litres just for themselves before you add tank mates.

Water parameters

The essential discus water parameters:

• Temperature: 28-30 degrees C (31 for breeding or disease)
• pH: 6.0-7.0, stable
• Hardness: 1-8 dGH (soft water)
• Ammonia / nitrite: zero, always
• Nitrate: below 20 ppm (large water changes handle this)

The high temperature requirement is the single biggest thing that shapes discus keeping. Most community fish top out at 26 C. At 28-30 C oxygen saturation drops, bacterial activity speeds up, and waste breaks down faster — which is why filtration and water changes become non-negotiable.

Filtration

Use oversized biological filtration with gentle flow. A canister filter rated for twice your tank volume is a good starting point — I run two 1200 L/h canisters on my 450-litre discus tank to spread media capacity and give redundancy if one fails. Spray bars or lily pipes diffuse the return, preventing the chaotic current that discus dislike.

Warm water holds less dissolved oxygen, so surface movement matters. Position one return just below the surface to create ripple without turbulence.

Substrate and decor

Bare-bottom tanks are popular for grow-out and breeding because they are easier to vacuum and keep clean. For display tanks, fine sand works well. Avoid coarse gravel where waste and uneaten food can settle out of reach.

Decor should include vertical wood — driftwood standing upright or angled — because discus orient around it naturally. Leaf litter adds the blackwater tannin look and drops pH slightly. For plants, stick to heat-tolerant species: Amazon swords, Anubias, Microsorum, Cryptocoryne wendtii, and floating plants to soften the light.

Lighting

Moderate, never harsh. 7-9 hours a day is plenty. Very bright LEDs without floating plant cover make discus nervous — they darken and hang in corners. A planted tank with floating cover, or subdued lighting over bare-bottom setups, brings out their best behaviour and colour.

Feeding

Discus diet is one of the areas where hobbyists disagree most, and the "beef heart controversy" has been running for 30 years. Here is my honest take.

Staple foods

A quality sinking discus granule or pellet, specifically formulated for the species, forms the base of my feeding. Modern discus pellets from brands like Tropical, Tetra, and Ocean Nutrition are nutritionally complete and far more convenient than home-made mixes. Feed adults twice daily; juveniles need 4-5 small meals to fuel growth.

Frozen foods

Frozen bloodworm, brine shrimp, mysis, and daphnia form 30-50% of my feeding rotation. Thaw in tank water, rinse, and feed small portions. Variety matters — rotating between 3-4 frozen foods supports colour, immune function, and breeding condition.

The beef heart question

Traditionally, discus breeders fed beef heart mixes — ground beef heart blended with shrimp, vegetables, and vitamin supplements. It drives fast growth and large adult size. It also pollutes water aggressively, with fat globules clogging filters and ammonia spikes if overfed.

Modern pellet formulations make beef heart optional rather than essential. I use a beef heart mix occasionally for conditioning breeding pairs, but my day-to-day feeding is pellet and frozen food only. If you go down the beef heart route, commit to additional water changes and aggressive filter maintenance.

Foods to avoid

• Cheap flake — breaks apart, pollutes water, insufficient protein
• Freeze-dried tubifex — historically linked to disease transmission
• Live tubifex from unknown sources — parasite risk
• Any oversized pellet — discus have small mouths for their body size

Parental care — the discus magic

This is the behaviour that makes discus uniquely fascinating among freshwater fish. After eggs hatch and fry become free-swimming, the parents produce a nutrient-rich mucus on their skin — and the tiny fry feed directly on this mucus for the first 10-14 days of life, clinging to the parents' bodies like miniature passengers.

It is genuinely one of the most remarkable sights in the freshwater hobby. The parents alternate grazing duties, flicking fry from one to the other with a body shake when they have had their fill. You will not find this behaviour in tetras, barbs, or most other fish you can keep at home.

For this reason, discus breeding is one of the most rewarding experiences in fishkeeping. It is also why stripping fry for artificial rearing (though sometimes done commercially) misses much of what makes the species special.

Tank mates

Discus tank mate selection is constrained by three things: temperature (28-30 C rules out most community fish), soft acidic water preference, and a gentle peaceful temperament that is easily outcompeted.

Ideal companions

• Cardinal tetras — the classic pairing. Thrive at 28 C, soft water, peaceful, add mid-water movement without stressing discus. A school of 20+ is standard in a discus community
• Sterbai corydoras — the only cory species that genuinely tolerates 28-30 C long-term. Essential bottom dwellers for a discus tank
• German ram cichlids — share the warm soft water preference, add colour and behavioural interest, generally peaceful in a large tank
• Rummy-nose tetras — another warm-water schooler, excellent water-quality indicator (their red noses fade with rising nitrate)
• Bristlenose plecos — tolerate the heat, keep algae down, do not bother discus
• Otocinclus — peaceful algae grazers, mature planted tanks only

Species to avoid

• Regular corydoras (paleatus, aeneus) — cannot tolerate 28-30 C long term
• Angelfish — can work in very large tanks but compete for food and sometimes introduce disease; see my note below
• Tiger barbs — chronic fin nippers, stress discus relentlessly
• Danios — too fast, too cool-water
• Bettas — temperament and feeding style mismatch
• Large cichlids — discus are peaceful, not predatory
• Most livebearers — prefer harder water

The angelfish question

Discus and angelfish are both South American cichlids and technically compatible on paper. In practice, angelfish are faster, more assertive at feeding, and a known vector for the parasite Spironucleus which can trigger hole-in-the-head in discus. I do not recommend the combination for most setups. If you must try it, use a 600L+ tank, quarantine angelfish for 6 weeks, and watch feeding dynamics carefully.

Breeding

Breeding discus is the advanced level of the hobby, and I have spent many late nights watching spawning couples with a cup of tea in hand. Here is the overview.

Getting a pair

You cannot sex juvenile discus reliably by appearance. The practical route is buying 6-8 juveniles and letting them grow out together — as they mature, pairs form naturally, and you will see a bonded couple begin to defend territory and clean surfaces together. Alternatively, proven pairs are sold by specialist breeders for 200-400 GBP.

Breeding setup

A separate 100-150 litre bare-bottom tank works well. Include one vertical surface — a cone, slate, or clean piece of filter pipe — as the egg site. Water should be very soft (1-3 dGH), pH 6.0-6.5, and 29-31 C. Sponge filter only, to avoid fry being sucked in.

Spawning and fry rearing

A bonded pair will clean the spawning surface repeatedly, then lay 100-300 eggs in neat rows. Both parents fan the eggs, removing any that turn white with fungus. Hatching takes 48-60 hours, with free-swimming fry appearing 3-4 days after that.

Once free-swimming, fry attach to the parents' skin and feed on mucus for 10-14 days. After that, introduce newly hatched brine shrimp gradually while the fry continue to nibble from the parents. Growth is slow — expect 6 months to reach sellable juvenile size.

Common breeding failures

• Young pair eating first 2-3 spawns — normal, they usually improve
• Eggs turning white — water too hard, or fertilisation failure
• Fry not attaching — parents too young or stressed
• Parent slime production inadequate — often nutritional

Health and disease

Discus are more disease-prone than most community fish because of their sensitivity and the warm stressed conditions in commercial trade. Understand the common problems and your success rate goes up dramatically.

Hole-in-the-head (HITH)

Small pits and erosions appear on the head and lateral line. Causes are debated but include poor water quality, Hexamita parasites, dietary deficiency (especially vitamins), and chronic stress. Treatment: improve water, ensure varied diet, metronidazole in food if parasitic involvement suspected.

Internal parasites

Hexamita, Capillaria, and various flagellates are common in imported discus. Symptoms include white stringy faeces, weight loss despite feeding, and listlessness. Treatment: metronidazole and levamisole in rotation, ideally under veterinary guidance.

Discus plague

A feared condition — likely a viral or bacterial stress response triggered when discus from different sources mix. Fish darken, produce excess slime, clamp fins, and may die within days. Prevention is everything: never mix unquarantined stock, keep groups source-matched, maintain stable conditions.

Ich (white spot)

Common after transport stress. Temperature at 28-30 C already speeds the parasite's life cycle. Treat with proprietary white spot medication and raise to 31 C for 10 days.

Prevention principles

• Quarantine all new discus for 4 weeks minimum, in a dedicated tank
• Never mix stock from different sources without separate quarantine
• Maintain warm stable water with large regular water changes
• Feed a varied diet to support immune function
• Observe daily — early intervention beats late treatment

UK delivery and acclimation

Shipping discus requires more care than any other tropical fish we handle. We dispatch Monday to Wednesday only, use insulated boxes with heat packs year-round, and double-bag each fish with oxygen. Delivery is tracked.

When your discus arrive, float the sealed bag in your aquarium for 20 minutes to equalise temperature. Then drip-acclimate over 45-60 minutes — discus need slower acclimation than most species because of their sensitivity to pH swings. I use airline tubing with a loose knot to control flow to about 2-3 drops per second.

Dim the tank lights for the rest of the day. Newly arrived discus will darken, hide, and refuse food for 24-48 hours. This is normal. Offer a small amount of food on the second day, expect hesitant feeding, and do not panic if they take 3-4 days to settle.

Starting your first discus tank — honest advice

If you have read this far and are still committed, here is what I wish someone had told me before my first group.

Start with German Stendker juveniles at 5-8 cm. They are the hardiest domestic strain, adapt well to tap water mixed with RO, and are affordable enough (40-70 GBP each) that a group of 6 is within reach for a serious hobbyist.

Cycle for 6 weeks minimum, with seeded media. Discus do not tolerate ammonia or nitrite spikes. A fully mature bacterial colony is the foundation.

Buy the group all at once from one source. Mixed-source groups are the most common cause of discus plague. One shipment, one quarantine, one introduction.

Plan the water change routine before you buy the fish. 30-50% weekly, twice weekly for juveniles. RO prep, remineralisation, temperature matching. If this schedule sounds unrealistic for your lifestyle, rethink.

Expect to lose one or two fish in the first 6 months. It is not failure — it is the reality of keeping sensitive advanced fish. Good husbandry minimises it but never eliminates it entirely.

Why buy discus from us

We hold all discus in dedicated warm soft-water systems at 28-30 C with RO-remineralised water. Every fish is assessed for feeding response, body shape, finnage, and disease signs before dispatch. We do not ship discus straight from the wholesaler — they are held for at least 14 days in our systems before being offered for sale.

Each order is packed specifically for sensitive cichlids: heavy-duty insulated boxes, double-bagged fish with oxygen injection, and heat packs in all but the warmest summer weeks. Tracked delivery minimises time in transit.

If you are building a serious discus display, our current discus listings include group-ready sizes and colour combinations suited to a long-term community. Email us before ordering a group of 6 and we will help you select compatible varieties and sizes.

Answers to common discus questions

What is the lifespan of a discus fish?

Well-kept discus typically live 10-12 years, with exceptional individuals reaching 15^[1]. The biggest lifespan factors are water stability, appropriate group size, and diet variety.

What size tank do discus need?

250 litres minimum for a group of 6, with 300-450 litres strongly preferred for long-term stability. Depth and vertical swimming space matter as much as total volume for this deep-bodied species.

What temperature do discus fish need?

28-30 degrees C for normal keeping, 31 for breeding or disease treatment^[2]. This high requirement limits compatible tank mates to warm-water specialists.

What are the best discus tank mates?

Cardinal tetras, sterbai corydoras, German ram cichlids, bristlenose plecos, and rummy-nose tetras. All tolerate the high temperature and peaceful discus temperament.

Are discus fish hard to keep?

Yes. They are advanced fish requiring warm soft water, large tanks, group living, and committed maintenance. With aquarium experience and the right setup, they are keepable; as a first fish, they are the wrong choice. See our first tropical tank guide for a more suitable starting point.

Where can I buy discus fish for sale in the UK?

Specialist retailers with heated dispatch and source-matched groups. Avoid general aquatic shops with mixed-source holding tanks. We hold our discus in species-dedicated warm soft-water systems — browse our current listings below.

How many discus should I keep together?

Six minimum. In smaller groups one fish nearly always gets bullied into decline. A group of 6-8 spreads social pressure and supports natural pair bonding.

Do discus need RO water?

In most UK regions yes, at least mixed with tap water. London, Cambridge, Portsmouth, and much of the south east have hard alkaline water that is unworkable for sensitive discus without RO. Manchester and parts of Scotland are softer and often usable straight. Check your water report.

What do discus fish eat?

Quality discus granules as a base, supplemented with frozen bloodworm, brine shrimp, and optionally beef heart mixes. Feed adults twice daily, juveniles 4-5 times daily in smaller portions.

What is the difference between discus and angelfish?

Both are South American cichlids but with different needs. Angelfish tolerate a wider temperature range (24-28 C), are more assertive, and more forgiving of water parameters. They are a better intermediate step toward discus rather than an ideal tank mate for them.

Can I keep a single discus?

Technically yes, but it is a miserable fish. Discus are highly social and a solitary individual shows reduced colour, appetite, and activity. Six is the proper minimum. If your tank cannot support six, discus are not the species for you.

How much do discus fish cost?

UK prices range from 35-60 GBP for small Asian-farmed juveniles, 50-100 GBP for German Stendker stock, 100-200 GBP for adult premium strains, and 200+ for wild-caught or proven breeding pairs. Budget for the group total plus ongoing costs — RO unit, remineralisers, heating bills, food.

Do discus fish need a heater?

Yes, and a reliable one. UK room temperatures will never sustain the 28-30 C discus require. I run an adjustable 300W heater plus a 100W backup in my 450L tank, because heater failure at discus temperatures is a fish-killing event.