Rainbow Emperor Tetra Breeding Guide
Breeding the Rainbow Emperor Tetra (Nematobrycon lacortei): sexing by eye colour and fins, soft-water pair spawning and batch-laid eggs.
Overview
The Rainbow Emperor Tetra (Nematobrycon lacortei) is a Colombian characid closely related to the Emperor Tetra, with intense iridescence and red eyes in males. Seriously Fish gives it a general range of about 20-28 C and pH 5.0-7.2, but for breeding the water is kept soft and acidic. It is an egg-depositing tetra without parental care; eggs are laid in small batches, so spawning may continue over several hours, after which the adults are removed.
Sexing
Seriously Fish reports clear dimorphism: males have red eyes and more extended dorsal, anal and caudal fins, and are generally more colourful, while females have blue-green eyes and a fuller body, especially when gravid.
Conditioning
Condition the fish in separate male and female groups. When the females are noticeably gravid, select a single pair for the spawning tank.
Breeding Setup
- Small, dimly lit spawning aquarium.
- Temperature about 24-27 C (75-80 F), pH 5.0-7.0, general hardness around 1-8.
- Fine-leaved plants or spawning mops, or a mesh base that lets eggs fall out of reach.
- Small air-powered sponge filter.
Spawning Behavior & Trigger
Introduce the pair in the evening; spawning typically follows the next morning. Eggs are deposited in small batches, so spawning may continue for several hours. The adults will eat their eggs and should be removed afterwards.
Egg & Fry Care
Eggs hatch in around 24-36 hours and the fry are free-swimming about 4-5 days later. Offer an infusoria-grade food for the first week or so, until the fry are large enough to accept microworm and Artemia (brine shrimp) nauplii.
Common Challenges
Because eggs are laid in small batches over several hours, total yields can be modest, and the adults must be removed to prevent egg predation. Soft, acidic water supports better fertilisation and hatch rates.