Breeding Glowlight Tetra
How to breed Hemigrammus erythrozonus, an egg-scattering tetra: sexing, soft acidic spawning setup, egg numbers, hatch time and rearing the light-sensitive fry.
Overview
Hemigrammus erythrozonus is an egg-scattering characin that gives no parental care; the adults will eat the eggs and should be removed as soon as eggs are noticed. Wikipedia describes it as bred in captivity with a moderate level of difficulty, matching the intermediate rating.
Sexing
Mature females are more rounded in the belly than males and tend to grow a little larger; the slimmer males are more colorful. Differences become clear only as fish mature and females fill with eggs.
Breeding Setup
- Separate spawning tank, around 18 x 10 x 10 inches, dimly lit
- Fine-leaved plants (java moss) or spawning mops, or a mesh base so eggs fall out of reach
- Soft, acidic water: pH 5.5-6.5, GH 1-5 (Wikipedia gives 6-8 dGH at 26-28 C)
- Temperature 80-84 F (27-29 C); peat filtration and RO water are recommended, with a small air-powered sponge filter
Spawning Behavior & Trigger
Condition the breeders on small live foods. For pair spawning, condition the sexes separately and move the fattest female and best male to the spawning tank in the evening; they should spawn the following morning. During spawning the male shows rapid swimming and fin-locking and the pair often roll, sometimes turning upside down. Females release about 120-150 eggs.
Egg & Fry Care
Remove the adults at once, as they eat eggs. The eggs and early fry are light-sensitive, so keep the tank dark; Seriously Fish gives a hatch time of 24-36 hours and Wikipedia 20-25 hours, with fry free-swimming 3-4 days post-hatch. First foods are infusoria, then microworm or brine shrimp nauplii. Orange striping appears by about three weeks.
Common Challenges
Achieving suitably soft, acidic water and protecting the light-sensitive eggs and fry are the main hurdles. The first-feeding fry are small and need infusoria-grade foods before they can take brine shrimp nauplii.