Discus
Symphysodon aequifasciatus
The majestic king of the aquarium, demanding warm, pristine water.
| Difficulty | Advanced |
| Min. Tank Size | 250 L |
| Temperature | 28.0–31.0 °C |
| pH Range | 5.5–7.0 |
| Max Size | 20.0 cm |
| Lifespan | 10-15 years |
| Diet | Carnivore |
| Temperament | Peaceful |
Overview
The Discus (Symphysodon aequifasciatus) is the majestic king of the aquarium, demanding warm, pristine water. It is one of the most recognisable members of the cichlids group kept by Australian aquarists, valued for its appearance, manageable adult size of around 20.0 cm and its peaceful nature.
This guide covers everything you need to keep the Discus successfully - ideal tank size and setup, water parameters, diet, suitable tank mates, breeding, how to tell males from females, and the health problems to watch for. Rated Advanced to care for, it can live for roughly 10-15 years when its needs are met.
Natural Habitat & Origin
This cichlid comes from the warm rivers, streams and floodplains of South America (and, for some species, West Africa), where it forms pairs and defends a territory among roots, rocks and leaf litter. It is an intelligent fish that rewards a thoughtfully aquascaped, stable tank.
Understanding where a fish comes from is the shortcut to keeping it well: matching the temperature, water chemistry and amount of cover it evolved with is far more effective than fighting against its nature.
Tank Size & Aquarium Setup
Provide a minimum of 250 litres for the Discus. Because it is a shoaling fish kept in groups, floor space and swimming length matter more than height.
Fit a lid to prevent jumping and to keep the tank warm and stable.
Live plants, driftwood and some shaded retreats give the fish security and show off its colours against a natural backdrop.
Mature, well-cycled biological filtration is essential before adding any fish. Match the filter's flow to the fish - moderate for most, stronger and more oxygenated for hillstream and riverine species.
Water Parameters
Keep the Discus in stable water at 28-31 °C with a pH of 5.5-7.0. Soft, acidic water brings out its best colour and is important for long-term health and any hope of breeding.
Test your water regularly: ammonia and nitrite must always read zero, and nitrate should be kept low (ideally under 20-40 ppm) with routine partial water changes. Sudden swings in temperature or chemistry cause far more illness than water that is slightly 'wrong' but stable, so always dechlorinate and temperature-match new water.
Diet & Feeding
The Discus is a carnivore. Base its diet on meaty foods - frozen or live bloodworm, daphnia, brine shrimp and a good carnivore pellet - rather than plant-based flakes it cannot fully digest.
Feed small amounts once or twice a day - only as much as the fish clears in a minute or two - and consider one fasting day a week. Overfeeding is the single most common cause of pollution and disease in home aquariums.
Temperament & Tank Mates
The Discus is an excellent peaceful community fish. It mixes happily with other calm species that share its temperature (28-31 °C) and pH (5.5-7.0) needs, are too large to be eaten, and are not large enough to eat it.
Keep it in a small group rather than singly; it is a social fish that is shyer and less active when kept alone.
Breeding
The Discus is an open substrate spawner that forms pairs and lays eggs on a cleaned flat rock or leaf. Both parents guard the eggs and shepherd the fry, showing impressive parental care.
Even if you do not plan to breed it, understanding this behaviour helps you recognise it in the tank and respond appropriately - for example by adding cover for fry or by giving a guarding pair some space.
How to Tell Males from Females
In many of these cichlids the male is larger with longer, more pointed fins and brighter colour, while the female is smaller and rounder; some species show clear breeding colours that make pairing easier.
Common Health Problems
Like most aquarium fish it is susceptible to white spot (ich), fin rot and fungal infections, almost always triggered by stress or poor water quality. It is sensitive to nitrate and bacterial infections, so frequent water changes and a mature tank are essential. Quarantine new arrivals for 2-4 weeks to keep your main tank disease-free.
Prevention is far easier than cure: keep water pristine, avoid overstocking and overfeeding, quarantine new arrivals for two to four weeks, and watch daily for early warning signs such as clamped fins, loss of appetite, flashing (rubbing on objects) or laboured breathing. Caught early, most problems are very treatable.
Is the Discus Right for You?
The Discus is a rewarding choice for fishkeepers with a little experience and a stable, mature tank, as long as you can provide at least 250 litres, water at 28-31 °C and pH 5.5-7.0, the right diet and a proper group of its own kind.
Get those basics right and you will enjoy a healthy, colourful Discus for around 10-15 years. For tank planning, try our free aquarium tools, and browse our fish, plant and disease guides to build the perfect community.