Female cardinal tetras release their eggs during the rainy season. The eggs become fertilized by the milt (sperm) of males in close proximity. Mating takes place at twilight during the rainy season. The male embraces the female while swimming. Fertilization is external. As the female scatters about 500 eggs into the water, males fertilize the eggs.

Mating System: polygynandrous (promiscuous)

Female cardinal tetras may release about 500 eggs. Once the eggs have been laid, they sink and some adhere to plants. Because cardinal tetra eggs are light sensitive, the only eggs that can develop into adult fish are released in a shaded river habitat. To breed cardinal tetras successfully in captivity, the pH should be between 5.5 and 6, the temperature should be at 24°C and the light should be dim. Fry are independent within 3 to 4 days of hatching. Both males and females reach sexual maturity by approximately 9 months of age.

Breeding interval: The breeding interval of these animals is not reported.

Breeding season: The spawning season of cardinal tetras in their natural environment is during the rainy season.

Average number of offspring: 500.

Range time to hatching: 24 to 30 hours.

Range time to independence: 3 to 4 days.

Average age at sexual or reproductive maturity (female): 9 months.

Average age at sexual or reproductive maturity (male): 9 months.

Key Reproductive Features: semelparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous

Parent cardinal tetras take no care of their eggs or young. After eggs are released, some parent cardinal tetras may even eat some of their spawn.

Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female)