Species feeding guide

Live food for rainbowfish

Rainbowfish fool breeders: the adults are hardy and greedy, but the fry hatch minuscule and grow slowly, spending their first weeks needing food barely bigger than infusoria. More rainbowfish spawns are lost to “nothing small enough to eat” than to any disease — which is why the fry cultures matter more for this family than for almost any other egg-layer.

A Lake Eacham rainbowfish (Melanotaenia eachamensis) in an aquarium

Photo: Martin F. Gomon, Wikimedia Commons, CC BY 4.0

The feeding plan

Stage	Feed this	Why it works
Fry, days 1–7	Vinegar eels	Among the few cultured foods small enough for newly hatched rainbowfish, and they swim in the surface film where rainbow fry feed
Fry, weeks 1–3	Banana worms, then microworms	The step up as mouths grow; banana worms cover the slowest fry while the bolder ones graduate
Fry, weeks 3–6	Newborn daphnia / moina	Where growth finally accelerates — fry on baby moina pull visibly ahead of fry held on worms
Adults	Daphnia 2–3 times a week	Triggers the chase-and-flash feeding rainbows are kept for, and conditions fish for the spawning mop

Practical tips

Have the eel tub climbing before eggs hatch — rainbowfish eggs take a week or more, which feels like plenty of time until day one arrives.
Feed fry at the surface in good light; rainbow fry hunt by sight in the top centimetre of the tank.
Raise fry in a small tank at first. A 20-litre grow-out with dense food beats a big tank where eels disperse and fry starve in plenty.

Watch out: Do not move rainbow fry onto dry food early because the biggest ones manage it — the runts quietly starve. Keep live food running until every fish in the tank is taking baby daphnia.

Common questions

What do rainbowfish fry eat first?

Vinegar eels — they are small enough for day-one rainbowfish and swim where the fry hunt. Follow with banana worms and microworms over weeks 1–3, then newborn daphnia (moina) for the growth phase.

Why do my rainbowfish fry keep dying in week one?

Usually starvation, not water: the fry are smaller than they look, and most “fry foods” are too big. A swimming food at the surface (vinegar eels), fed little and often in a small tank, fixes most first-week losses.

Is daphnia good for adult rainbowfish?

Excellent — it is the feed that gets a rainbow tank flashing and chasing. Moina-sized daphnia suits even the smaller rainbow species, and regular live feeds condition fish for breeding.