Feather-fin Tetra (Hemigrammus unilineatus) Breeding Guide
Breeding Hemigrammus unilineatus, a widespread egg-scattering characin reputedly easy to reproduce: soft acidic water, fine-plant spawning and light-sensitive eggs.
Overview
Hemigrammus unilineatus is a widespread characin from Central and South America, recorded across Trinidad and Tobago, Venezuela, the Guianas, Peru, Brazil and the Amazon and Guaporé basins. FishBase describes it as gregarious, non-aggressive and reputedly easy to rear and reproduce in the aquarium. It is an egg-scatterer in the manner of other Hemigrammus and gives no parental care.
Sexing
Sexes can be distinguished by the shape of the swim bladder seen through the body: it tapers to a point in males and is rounded in females. Adult females also tend to be slightly larger and more heavy-bodied than males.
Conditioning
Condition the group on plenty of small live foods. The species can be spawned in a group of around six of each sex or in selected pairs once the females are gravid.
Breeding Setup
- Spawning tank around 18 x 10 x 10 inches, kept very dimly lit.
- Soft, acidic water: pH 5.5-6.5 and hardness around 1-5 gH; peat filtration and reverse-osmosis water help.
- Temperature approximately 27-29 C (80-84 F); the species tolerates 23-28 C.
- Clumps of fine-leaved plants such as java moss or spawning mops, or a mesh base to protect the eggs.
- A gently bubbling air-powered sponge filter.
Spawning Behavior & Trigger
Eggs are scattered among plants or fall through a protective mesh. Soft acidic water and subdued lighting are the main triggers. Adults should be removed once eggs are seen, as they will eat them.
Egg & Fry Care
Eggs hatch in 24-36 hours and the fry become free-swimming about 3-4 days later. Eggs and fry are light sensitive early on, so keep the tank dark where possible. Feed first with infusoria-type foods, then microworm or brine shrimp nauplii.