Cardinal Tetra Origin and Appearance
The cardinal tetra (Paracheirodon axelrodi) comes from the black-water tributaries of the Rio Negro and upper Orinoco basins in South America, where huge shoals move through dense, tannin-stained water. In the aquarium it’s instantly recognisable by the vivid, iridescent blue-green stripe that runs the full length of its body, sitting above a broad band of deep red that also extends from nose to tail. This is the easiest way to tell a cardinal tetra apart from its close relative, since a neon tetra only shows red on the rear half of its body.
Cardinal Tetra Tank Requirements
Cardinal tetras are a true shoaling fish and should always be bought in groups of six or more, ideally ten or more if your tank allows, as they feel far more secure and show much better colour in a larger group. A planted tank of 60 litres upwards with subdued lighting and some floating plants suits them well, echoing the shaded black-water streams they come from. Water should be kept stable at 22-26°C, slightly soft and neutral to slightly acidic, with mature, well-cycled filtration, cardinal tetras are noticeably less tolerant of new or unstable water than many other community fish, so it’s worth waiting until your tank has fully settled before adding them.
Feeding Cardinal Tetras
Cardinal tetras are easy-going eaters that will readily take high-quality flake and micro pellets, though they really come into their own colour with the occasional small frozen food such as daphnia or brine shrimp added to their diet. Feed small amounts a couple of times a day rather than one large feed, as their tiny mouths mean they can only manage small portions at a time.
Cardinal Tetra Tank Mates
Being a peaceful, small shoaling fish, cardinal tetras mix well with other calm community species such as Corydoras, dwarf gouramis, small livebearers and other tetras, but should be kept away from larger or boisterous fish that might see them as a snack. Take a look at our full range of tetra fish if you’re planning a mixed shoal, or our wider selection of tropical fish for sale for other suitable community tank mates.
For more on tetras and other small shoaling fish, see our guide to the best tetras for community tank setups and our guide to emperor tetra care.
Cardinal Tetra FAQs
How many cardinal tetras should I keep together?
A minimum of six, though a group of ten or more will shoal more naturally and show better colour.
Are cardinal tetras hard to keep?
Not for an established tank, but they’re less forgiving of new, unstable water than some other community fish, so it’s best to add them once your tank has fully cycled.
Do cardinal tetras and neon tetras get along?
Yes, they’re closely related, similarly sized and have matching care needs, so they can be shoaled together or kept separately without any issues.