Cobalt Blue Discus
Symphysodon aequifasciatus
The Cobalt Blue Discus (Symphysodon aequifasciatus) is a semi-aggressive fish that's best left to experienced keepers. Give it a tank of at least 280 litres (74 US gallons), water held at 81-88°F, and a pH of 6-7.5. Always keep a group of at least 6 - they feel safest in numbers.
Captive lifespan reflects typical experience in a home aquarium, not maximum recorded age; genetics, sourcing, and care vary.
Natural distribution
South America
- South America
Regional colours match the stocking calculator's origin map.
Cobalt Blue Discus Tank Setup
Give them at least 280 litres (74 US gallons). Cichlids are territorial and produce plenty of waste, so strong filtration and some rocks or wood to break up sight lines both help. Aim for 81-88°F and a pH around 6-7.5. Always keep a group of at least 6 of their own kind - kept alone or in pairs they tend to turn shy, nippy, or wash out in colour. They reach about 20 cm as adults, so don't be misled by the small juveniles sold in stores.
What Do Cobalt Blue Discus Eat?
They're meat-eaters, so feed good-quality frozen or gel foods rather than relying on generic flake. Go easy on portions - leftover protein fouls the water faster than plant foods do.
Cobalt Blue Discus Tank Mates
Captive-bred Discus morph. Requires pristine water conditions; zero tolerance for nitrates. Species/community with small calm fish only. The Cobalt Blue Discus is semi-aggressive, which is the first thing to weigh up when you choose tank mates. At around 20 cm fully grown, it needs tank mates that can hold their own against its size and appetite. It's a shoaling fish, so settle a group of 6 or more of its own kind before adding anything else - a stressed, lonely fish is far more likely to nip or hide. Before you buy, run your full stocking list through our stocking calculator. It weighs temperament, adult size, and water needs together, which a single species page can't do on its own.
Are Cobalt Blue Discus Good for Beginners?
Not a sensible first purchase. Get the tank cycled, keep easier fish stable for a year, then revisit if you still want the extra work this species demands.
Cobalt Blue Discus - frequently asked questions
What size tank do Cobalt Blue Discus need?
Cobalt Blue Discus need a tank of at least 280 litres (74 US gallons). A bigger tank is always easier to keep stable, and gives them more room to settle in and behave naturally.
How many Cobalt Blue Discus should I keep together?
Keep a group of at least 6. Cobalt Blue Discus are a shoaling species and become stressed, lose their colour, or hide when kept singly or in pairs.
What water parameters do Cobalt Blue Discus need?
Keep them at 81-88°F with a pH of 6-7.5, steady rather than chased to an exact figure. In a cycled tank, ammonia and nitrite should both read 0 ppm, with nitrate kept low through regular water changes.
What do Cobalt Blue Discus eat?
Cobalt Blue Discus are meat-eaters. Feed good-quality frozen or gel foods rather than relying on generic flake, and don't overfeed. Feed small amounts once or twice a day, and remove anything they don't eat.
Are Cobalt Blue Discus good for beginners?
Cobalt Blue Discus are not a beginner species. They need precise conditions and consistent maintenance, so build experience with hardier fish before keeping them.
Common mistakes with Cobalt Blue Discus
- Buying fewer than 6 - Cobalt Blue Discuss need a proper school to feel secure; isolated individuals hide, fail to colour up, or become stressed.
- Underestimating tank size - the minimum footprint is 280 litres (74 US gallons); impulse buying into a smaller tank leads to stress and shortened lifespan.
- Cool tap water - this species needs 81-88°F; cold acclimation suppresses immune response and often triggers disease outbreaks.
Building a community? Run the full list through the stocking calculator before you add anything else.
Great tank mates
Chosen from temperament, overlapping temperature/pH bands, plausible minimum tank footprints, and size versus yours in App-aquatic data. Hobby nuance always wins - verify stocking and temperament before purchasing.
Fish to avoid mixing with Cobalt Blue Discus
These well-known species are commonly sold alongside this fish but are not recommended tank mates - verify before purchasing.
- Betta (Male)Predator - Betta (Male) will eat or injure smaller tank mates
- Cardinal TetraSize risk - Cobalt Blue Discus will likely eat Cardinal Tetra at adult size
- Common GoldfishGoldfish - prefer cooler, harder water that tropical fish cannot tolerate
