Breeding / Egg scatterers

Egg scatterers · Moderate

Breeding the harlequin rasbora

Pairs attach small batches of eggs to the underside of broad leaves; eggs hatch in 24-48 hours and fry swim freely after about a week.

Full species page

Step by step

Pairing

Buy a group of 8-10 and let them pair up. Condition on live foods.

Breeding tank

30-40 L tank with soft acidic water (pH 5.5-6.5), broad leaves like Cryptocoryne and dim light.

What starts it

Soft acid water, warm temperature and conditioning with live foods.

Eggs and young

Around 50-100 eggs on leaves; hatch in about 24-36 hours.

Raising the fry

Feed infusoria, then baby brine shrimp. Fry are sensitive; keep water soft and clean.

Common mistakes

Hard water
Not enough broad leaves
Poor conditioning

Setup blueprint

Home setup

One breeding tank for the harlequin rasbora, drawn to scale from the breeding guide.

Breeding tank: 30 L · about 45 × 25 × 30 cm, 30–40 L from the breeding guide
Sponge filter and air pump · gentle and safe for eggs and fry
Heater, 22–27 °C · this species' normal range
Slate or flat stone · named in the guide
Dim light, covered sides · from the guide

Water: 22–27 °C · pH 5.5–6.5 · soft water

A plan from the breeding guide and an adult size of 4.5 cm. Tank shape is a standard 2 : 1 : 1.2 box, at least 6 adult lengths long. Check each step in the guide above.

Setup blueprint

Business setup

A 120 cm rack for breeding the harlequin rasbora in numbers.

2 breeding tanks, 30 L each · about 45 × 25 × 30 cm, set up like the home tank
2 grow-out tanks, 60 L each · about 60 × 30 × 35 cm; twice the breeding tank, never smaller than this species' smallest tank
Shared air pump and air line · one line along each shelf feeds a sponge filter in every tank
Heat the room or each tank · 22–27 °C

In total: 4 tanks, about 180 L of water. A litre of water weighs about 1 kg, so check that the floor and rack can take the weight.

Sizes are worked out from the breeding tank in the guide. Tanks fit a standard 120 cm rack when they can; bigger tanks go on their own stands.

Male or female

Males are slimmer and more colourful with a sharper-edged black triangle; females are rounder-bellied, often a little larger, with a more rounded triangle.

Can I breed it in my tank?

Your tank (litres of water)

Use a separate small tank with a sponge filter and spawning mops, so the eggs aren't eaten.
Takes some experience.

Day-by-day plan

Typical for egg scatterers

Spawning date

14 days beforeCondition the parents
Feed live or frozen food twice a day. Keep males and females apart if you can.
Day 0Spawning
Eggs are scattered over mops or fine plants, often at first light. Remove the parents straight after.
Day 1Eggs hatch
Most eggs hatch in 1–2 days. Keep the tank dim and remove white (fungused) eggs.
Day 4Free swimming, first food
Fry use up the yolk and start swimming. Feed infusoria or liquid fry food several times a day.
Day 8Baby brine shrimp
Switch to newly hatched brine shrimp or microworms. Start small, daily water changes.
Day 21Crushed flake
Add finely crushed flake. Sort fry by size so the big ones don't eat the small ones.
Day 60Ready to move
Most small fish reach about 2 cm in 2–3 months and can join the main tank.

A general guide for this breeding type. Days change with temperature and species.

Simulator: guided

Stage 1 of 7Condition the parents

Feed live or frozen food twice a day. Keep males and females apart if you can.

Simulator: try it yourself

Set up a virtual breeding tank and see what would likely happen.

Temperature: 25 °C

Condition with live or frozen foodBig, cool water changePlants, mops or a breeding boxRemove the parents after spawning

No spawning

Without live or frozen food the parents aren't in breeding condition.

An educational estimate from the breeding rules, not a promise.