Cardinal Tetra

Wider red stripe than a neon and a taste for warmer, softer water. Cardinals need a mature tank and groups of eight or more to show their best color.

• Minimum footprint: 20 gallons; a 25+ gallon tank gives real swimming room.
• Preferred swimming zone: middle of the water column.
• Social — keep a group of at least 6.
• Care level: moderate.

• Temperature: 73–82°F
• pH: 5–7
• Hardness: 1–6 dGH (Soft)

Stable parameters matter more than perfect ones — aim for consistency before chasing an exact number.

peaceful

schoolingpeacefulsoft-watermidwatersensitive

An omnivore — offer a staple flake or pellet plus regular frozen or live foods (daphnia, bloodworm, brine shrimp) and some vegetable matter for balance.

• Neon Tetra
• Guppy
• Bronze Corydoras
• Harlequin Rasbora
• Zebra Danio
• Platy

A further 1 species pair with Cardinal Tetra as conditional — workable with the right tank and precautions.

• Angelfish — Occasional chasing or fin nipping is possible.
• Molly — pH requirements do not intersect — one species will be stressed.
• Electric Blue Acara — Occasional chasing or fin nipping is possible.

Standard tanks at or above the recommended 25 gallons:

• 29 gallon 30 × 12 × 18″
• 30 gallon 36 × 12 × 16″
• 40 gallon Breeder 36 × 18 × 16″
• All tank sizes

• Start from a 20 gallon minimum and plan the full group size (6+) before you buy.
• Activity level is high, which affects how much of the tank it uses and how much it adds to the bioload.
• Zoning matters: this species lives mostly in the middle zone, so choose tank mates that occupy other levels.

Compatibility depends on tank size, water chemistry, temperament, and adult size. Run a full check against any species in our database.

In-depth guides for Cardinal Tetra:

• Cardinal Tetra and Neon TetraGood Match
• Cardinal Tetra and AngelfishNot Recommended
• Cardinal Tetra and Bolivian RamRisky
• Cardinal Tetra and German Blue RamRisky
• Cardinal Tetra and Harlequin RasboraGood Match

• FishBase(Scientific Database, accessed 2026-09-20)
• SeriouslyFish(Specialist Publication, accessed 2026-09-20)
• Aquarium Forge editorial guidelines(Editorial Interpretation, accessed 2026-09-22)

Data reviewed: September 2026 · Data version: 2026.11
Editorial note: Minimum tank recommendations may vary by source and husbandry approach. Our figures synthesise the sources above for planning purposes.