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Fish profile · Characidae
Cardinal tetra
Paracheirodon axelrodi
A blue-and-red shoaling fish native to the upper Orinoco and Negro river systems. The red lower flank extends much farther forward than in a neon tetra; it is kept in planted and blackwater aquariums.
Last reviewed 13 October 2026 · 5 sources
- Max length
- 5 cm
- IUCN
- LC
- Least Concern
- Family
- Characidae
- order Characiformes
Category from the IUCN Red List, via GBIF (CC BY 4.0); it may lag the latest Red List assessment.
How big?
Linear scale · hand 18 cm
Up to 5 cm.
How to identify
- Bright blue stripe across the side.
- Vivid red covers the lower flank almost from head to tail.
- Small body, reaching about 5 cm in the cited aquarium guide.
Look-alikes
Neon tetraThe neon tetra has a shorter red band limited mostly to its rear half.
Habitat
Blackwater rivers and tributaries.
- Diet
- Small worms and crustaceans; aquarium fish take varied small prepared and frozen foods.
- Native range
- Upper Orinoco and Negro river basins in South America.
Aquarium care
- Minimum tank
- 60 L
- Temperature
- 24–28°C
- pH
- 5.5–7.5
- Temperament
- Peaceful
- Group size
- 6+
Sources
Last reviewed 13 October 2026