Breeding Boesemani Rainbowfish
Breeding Melanotaenia boesemani: a continuous egg-scattering rainbowfish. Sexing colourful males, alkaline water, spawning mops, thread-attached eggs and a 7-12 day hatch.
Overview
Boeseman's Rainbowfish (Melanotaenia boesemani) is a rainbowfish of family Melanotaeniidae endemic to the Ayamaru Lakes on the Bird's Head (Vogelkop) Peninsula of West Papua, Indonesia. It is an egg scatterer that spawns over several weeks, and the KB record rates breeding difficulty as intermediate.
Sexing
Mature males are considerably larger and more vibrant than females and develop a notably deeper body as they mature. Males display constantly to one another when in spawning condition, while females become visibly plumper.
Conditioning
The adults are best conditioned as a group in a separate aquarium with plenty of live and frozen foods.
Breeding Setup
Use a breeding tank of at least 30″ in length with slightly hard, alkaline water, a small air-powered filter for oxygenation and no substrate. Reported parameters are about pH 7.5 at 27-29 °C (80-84 °F). Fine-leaved plants such as java moss or nylon spawning mops serve as the spawning medium.
- Temperature: 27-29 °C (80-84 °F)
- pH: around 7.5, slightly hard and alkaline
- Spawning medium: java moss or nylon mops
- Tank: 30″ minimum, no substrate
Spawning Behavior & Trigger
Rather than a single large spawn, the species lays batches of eggs daily over several weeks; the eggs attach to surfaces via small threads. Mops can be removed and replaced regularly so eggs can be reared away from the adults.
Egg & Fry Care
Eggs hatch in 7-12 days depending on temperature. Newly hatched fry require infusoria-type foods initially, then graduate to free-swimming foods such as brine shrimp nauplii after about one week. Because the fry stay near the surface, sinking foods are unsuitable.
Common Challenges
Spawning itself is not difficult, but the fry can be challenging to raise, in part because they stay at the surface and need very small, floating first foods.