What tank size does a Cardinal Tetra need?

A Cardinal Tetra needs an aquarium of at least 75 litres (19.8 US gallons) with a footprint at least 60 cm (23.6 in) long — for this species, swimming length matters as much as raw volume.

What water parameters does a Cardinal Tetra need?

Cardinal Tetra does best at 23–29 °C (73.4–84.2 °F), pH 4–6.5 and a general hardness of 0–8 °dGH.

What group size does a Cardinal Tetra need?

Cardinal Tetra is a social species — keep a group of at least 6 so natural behaviour emerges and stress stays low.

Is the Cardinal Tetra suitable for beginners?

Cardinal Tetra sits in the middle of the difficulty scale — manageable for a careful beginner who has done the reading, but it has specific needs worth researching first.

Species library

Cardinal Tetra

Paracheirodon axelrodi

Characidae

FishDifficulty: ●●●○○Data: well-established

📷 CHUCAO · CC BY-SA 3.0 · resized · Wikimedia Commons

Cardinal Tetra — Paracheirodon axelrodi — 📷 CHUCAO · CC BY-SA 3.0 · resized · Wikimedia Commons

About

The cardinal tetra is a dazzling blackwater characin from the Rio Negro and Orinoco drainages of South America. It differs from the similar neon tetra in that the red stripe runs the full length of the body. It demands warm, very soft, acidic water to truly thrive long-term, making it slightly more challenging than the neon. A peaceful, tightly shoaling fish that looks spectacular in large groups against dark substrate and dense planting.

Care

Provide warm (25–29 °C), very soft, acidic water and keep in shoals of 6+ (ideally 10+). Best suited to mature, softwater or blackwater-style tanks. Unlike the neon tetra it stays comfortable at the top of that range, which is why it is the classic discus dither fish.

Diet

Omnivorous micro-predator; feed small dry foods plus regular frozen and live micro-foods for colour and condition.

Tankmate compatibility

Computed by the AquaSage engine for a spacious reference tank — always check the full verdict for your exact setup in the calculator.

Full tank-mates guide with reasons →

Telling males from females

What works for this species, most reliable first.

Belly depthA hint only · only on well-fed adults, and only as a comparison
For most tetras, barbs and rasboras this is all there is: a conditioned female is deeper through the belly than a male of the same length.

All the methods, with diagrams

Also in these lists

Shrimp-safe fish Peaceful community fish Fish for a 112 litre tank

Frequently asked questions

What tank size does a Cardinal Tetra need?: A Cardinal Tetra needs an aquarium of at least 75 litres (19.8 US gallons) with a footprint at least 60 cm (23.6 in) long — for this species, swimming length matters as much as raw volume.
What water parameters does a Cardinal Tetra need?: Cardinal Tetra does best at 23–29 °C (73.4–84.2 °F), pH 4–6.5 and a general hardness of 0–8 °dGH.
What group size does a Cardinal Tetra need?: Cardinal Tetra is a social species — keep a group of at least 6 so natural behaviour emerges and stress stays low.
Is the Cardinal Tetra suitable for beginners?: Cardinal Tetra sits in the middle of the difficulty scale — manageable for a careful beginner who has done the reading, but it has specific needs worth researching first.

Sources

Water & tank

Temperature23–29°C

Optimal temp.25–29°C

pH4–6.5

Hardness (GH)0–8°d

Carbonate (KH)0–4°d

Adult size4.5 cm

Min. volume≥ 75 L

Min. tank length≥ 60 cm

Group size≥ 6

Swimming zoneMid

TemperamentPeaceful

Water typeFreshwater

FlowLow

Lifespan~5 yrs

Try in the calculator