Cardinal Tetra
Paracheirodon axelrodi
The Cardinal Tetra (Paracheirodon axelrodi) is a peaceful fish that's easy to keep. Give it a tank of at least 60 litres (16 US gallons), water held at 73-84°F, and a pH of 5.5-7.5. 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
Upper Rio Negro and Orinoco basins of Brazil, Colombia and Venezuela - blackwater South America.
- South America
Regional colours match the stocking calculator's origin map.
Cardinal Tetra Tank Setup
Give them a tank of at least 60 litres (16 US gallons). As open-water swimmers they care more about swimming length than height, so a longer tank is ideal. Keep the water at 73-84°F with a pH around 5.5-7.5, and avoid sudden swings. 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.
What Do Cardinal Tetras Eat?
They have small mouths, so stick to small foods: crushed flake, fine granules, and now and then a treat of frozen or live foods such as daphnia or baby brine shrimp. Anything too large simply gets ignored.
Cardinal Tetra Tank Mates
Keep in groups of at least 6. The Cardinal Tetra is peaceful, which is the first thing to weigh up when you choose tank mates. 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 Cardinal Tetras Good for Beginners?
Often recommended to beginners, but only after the tank is cycled and you can keep a proper school - not three fish in a new setup.
Cardinal Tetra - frequently asked questions
What size tank do Cardinal Tetras need?
Cardinal Tetras need a tank of at least 60 litres (16 US gallons). A bigger tank is always easier to keep stable, and gives them more room to settle in and behave naturally.
How many Cardinal Tetras should I keep together?
Keep a group of at least 6. Cardinal Tetras are a shoaling species and become stressed, lose their colour, or hide when kept singly or in pairs.
What water parameters do Cardinal Tetras need?
Keep them at 73-84°F with a pH of 5.5-7.5, 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 Cardinal Tetras eat?
Cardinal Tetras have small mouths, so they need small foods. Crushed flake and fine granules form the staple, with the occasional treat of frozen or live foods such as daphnia or baby brine shrimp. Feed small amounts once or twice a day, and remove anything they don't eat.
Are Cardinal Tetras good for beginners?
Yes - Cardinal Tetras are a good beginner choice once the tank is fully cycled and you can keep a proper group. They are hardy but still need stable water and a school to feel secure.
Common mistakes with Cardinal Tetras
- Buying fewer than 6 - Cardinal Tetras need a proper school to feel secure; isolated individuals hide, fail to colour up, or become stressed.
Guides that pair with this fish
- Cardinal tetra care guide - Parameters, plants, and group size.
- Cardinal tetra tank mates - Pairings that stay peaceful.
- Neon vs cardinal tetra - Which stripe pattern fits your tank.
- Angelfish with small tetras - Risk framing if you mix tall cichlids and tetras.
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 Cardinal Tetras
These well-known species are commonly sold alongside this fish but are not recommended tank mates - verify before purchasing.
- OscarPredator - Oscar will eat or injure smaller tank mates
- Pea PufferPredator - Pea Puffer will eat or injure smaller tank mates
- Betta (Male)Predator - Betta (Male) will eat or injure smaller tank mates
