No photo yet
Sign in to submit the first photo
Cardinal Tetra
Paracheirodon axelrodi
Animalia›Chordata›Actinopterygii›Characidae
📍 Rio Negro & Orinoco, South America
Often confused with the neon tetra, the cardinal tetra has a longer red stripe extending the full length of the body. It prefers soft, acidic blackwater conditions and looks stunning in large schools against dark substrate and dense planting.
Care Guide
Diet
Cardinal tetras are omnivores that thrive on a varied diet of high-quality micro pellets and flake foods as staples. Supplement 2-3 times weekly with live or frozen foods such as daphnia, micro worms, and brine shrimp to enhance coloration and maintain optimal health. Feed small amounts once daily, only what they can consume in 2-3 minutes.
Behavior
Cardinal tetras are peaceful, active schooling fish that display their best colors and behavior when kept in groups of 6 or more. They occupy the mid-water column and are most active during daylight hours, constantly moving through planted areas and open spaces. They are non-aggressive toward other peaceful species and show minimal territorial behavior.
Breeding
Breeding cardinal tetras in captivity is difficult and rarely successful in home aquariums. They require very soft, acidic blackwater conditions (pH 4.5-5.5, 1-2 dGH) and specific triggers like cooler temperatures and extended photoperiods. Fry are extremely small and require infusoria and microscopic foods, making large-scale breeding impractical for most hobbyists.
Tank Mates
Peaceful bottom-dweller with identical soft water requirements; excellent algae control without competing for food
Similar size, temperament, and water parameter needs; both prefer soft, acidic conditions and dense planting
Smaller tetra with compatible peaceful nature; prefers slightly warmer temperatures but overlaps well in community settings
Low-growing foreground plant that creates ideal habitat structure; provides shelter and natural aesthetic cardinal tetras prefer
Hardy, low-light plant that thrives in soft water; creates mid-level cover without requiring high maintenance
Peaceful invertebrate compatible with soft water; may predate on fry but safe with adults; adds visual interest
Common Diseases
Ich (Ichthyophthirius multifiliis)
White spots on body and fins, rapid breathing, lethargy, rubbing against objects
Raise temperature gradually to 28-29°C, perform daily 25% water changes, use aquarium salt (1 tsp per 5 gallons) or ich-specific medication; maintain for 10-14 days
Fin Rot
Frayed or deteriorating fin edges, discoloration at fin bases, progressive fin loss
Perform 50% water change immediately, improve water quality and filtration, treat with antibacterial medication; remove any sharp decorations causing injury
Neon Tetra Disease
Loss of coloration, curved spine, lethargy, white stripe along lateral line becomes cloudy
No cure exists; isolate affected fish to prevent spread, maintain pristine water conditions, euthanize severely affected individuals to prevent transmission
Bacterial Infection
Cloudy eyes, open sores, torn fins, loss of appetite, color fading
Perform 50% water change, treat with broad-spectrum antibiotic medication, improve water quality, isolate if spreading to other fish
Community Photos
0 photosPhotos are added when members log a tank with this species and upload a photo in their tank journal. Add your own tank to contribute.
No photos yet — add a tank with Cardinal Tetra to be the first!
Sign in to vote.
Tips from the community 💡
0 tipsReal experiences, care advice, and keeper notes. Finn learns from these too.
Sign in to share your experience.
No community tips yet — be the first to share your knowledge!
Quick Facts
- diet
- Omnivore – micro pellets, flake, daphnia, micro worms
- lifespan
- 4–5 years
- max size
- 5 cm (2 in)
- tank size
- 20 gallons minimum
- school size
- 6+
- temperament
- Peaceful, schooling
Water it likes
- ph
- 4.5–6.5
- ammonia
- 0 ppm
- nitrate
- <10 ppm
- hardness
- 1–6 dGH
- temperature
- 73–81°F (23–27°C)