Cardinal tetra (Paracheirodon axelrodi) care guide

Group
Freshwater fish
Other names
Cardinal, Red neon
Family
Acestrorhamphidae (American tetras; formerly Characidae)
Origin
Rio Negro and upper Orinoco drainages of Brazil, Colombia and Venezuela, in slow forest streams, flooded forest and blackwater tributaries.
Water
freshwater
Maximum size
3.5 cm
Temperature
23–29°C
pH
4–7
Hardness
Very soft to medium, 1–12 dGH
Minimum tank
54 litres
Care level
intermediate
Temperament
peaceful

Care

Cardinals are a shoaling fish and should be kept in a group of at least 8–10; larger groups look spectacular. A tank with a base of at least 60 × 30 cm (around 54 litres) is the minimum. A heavily planted, natural-looking set-up suits them best: a sandy substrate, driftwood, some dried leaf litter and subdued lighting, with shade-tolerant plants such as Java fern and Java moss. They come from warm, soft, acidic blackwater, so aim for about 23–29 °C, soft water and a pH on the acidic side of neutral. Wild-caught fish in particular do best in soft, acidic water. They need a mature, stable tank and do not cope well with poor or swinging water quality, so they are better added once the aquarium is well established. They also like warmer water than neon tetras, which is worth remembering if you mix the two. Although cardinals are now farmed in quantity, a large share of those sold are still wild-caught, much of it through sustainable community fisheries on the Rio Negro such as Project Piaba. In the wild they are almost annual fish, but they live considerably longer in a well-kept aquarium. Many cardinals are still wild-caught in the Rio Negro (around 20 million a year), and the fishery around Barcelos, Brazil, supports local livelihoods; captive-bred fish are becoming more common. Sources: Seriously Fish (seriouslyfish.com/species/paracheirodon-axelrodi/); FishBase (fishbase.se/summary/Paracheirodon-axelrodi.html); Wikipedia (en.wikipedia.org/wiki/Cardinaltetra). Checked October 2026.

Diet

An omnivore that feeds on tiny invertebrates in the wild. Use a good small flake or micro-pellet as the staple, with regular live or frozen foods such as bloodworm, mosquito larvae and Daphnia for condition and colour.

Breeding

An egg-scatterer with no parental care. Use a separate, dimly lit tank with fine-leaved plants or spawning mops and very soft, acidic water (pH 5.5–6.5, 1–5 dGH) at 26.5–29 °C. Condition the pair or group well; females are noticeably rounder and slightly larger than males. Remove adults after spawning. Eggs hatch in 24–36 hours and the fry become free-swimming 3–4 days later, needing infusoria at first before moving on to slightly larger foods.

Compatibility and tank mates

Peaceful and a superb community fish for softer water. Keep with other small, calm fish such as tetras, pencilfish, hatchetfish, Corydoras, small plecos and dwarf cichlids like Apistogramma. Avoid any fish big enough to eat them.

Last updated 4 October 2026. Community-edited care guide on Aquatic-Auctions.

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