Breeding / Livebearers

Livebearers · Moderate

Breeding the four-eyed fish

Livebearer (viviparous). Gestation is about 12 weeks; the young are born fully formed at 4-5 cm and can eat large food at once. Gravid females turn hostile just before giving birth, and premature births are a common problem.

Full species page

Step by step

Pairing

Pair a left- and right-handed fish.

Breeding tank

Wide, shallow tank with half-filled depth, brackish water and a lid.

What starts it

Brackish water, warm temperature and live food.

Eggs and young

Wild females carry 1-37 embryos (mean 12); after about 12 weeks' gestation the young are born at about 4.5-5 cm.

Raising the fry

Feed baby brine shrimp, flies and chopped insects.

Common mistakes

Keeping in fresh water
A deep narrow tank
Pairing same-handed fish

Setup blueprint

Home setup

One breeding tank for the four-eyed fish, drawn to scale from the breeding guide.

Breeding tank: 304 L · about 180 × 40 × 45 cm, the guide gives no size, so this is the smallest tank for this species
Sponge filter and air pump · gentle and safe for eggs and fry
Heater, 25–31 °C · this species' normal range
Plants for cover · typical for this breeding type
Breeding box · keeps newborn fry away from the adults; typical for this breeding type
Lid · from the guide

Water: 25–31 °C · pH 7.5–8.5

A plan from the breeding guide and an adult size of 30 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 row of tanks on their own stands for breeding the four-eyed fish in numbers.

1 breeding tank, 304 L · about 180 × 40 × 45 cm, set up like the home tank
2 grow-out tanks, 608 L each · about 180 × 55 × 65 cm; twice the breeding tank, never smaller than this species' smallest tank. Sort the young by size and sex here
Shared air pump and air line · one line along each shelf feeds a sponge filter in every tank
Heat the room or each tank · 25–31 °C

In total: 3 tanks, about 1,520 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 have a prominent scaled, tube-shaped gonopodium; females grow considerably larger. The usual claim that males and females are 'left- or right-sided' and must be paired opposite is unproven; keepers report the gonopodium is flexible.

Can I breed it in my tank?

Your tank (litres of water)

Takes some experience.

Day-by-day plan

Typical for livebearers

Birth date

28 days beforePregnancy
A dark 'gravid spot' grows behind the belly. Gestation is usually about 4 weeks.
Day 0Birth
Fry are born ready to swim. Thick plants or a breeding box keep them safe from adults.
Day 0First food
Feed crushed flake, baby brine shrimp or microworms 3–5 times a day.
Day 28Sexing starts
Males start to show color and a pointed anal fin. Separate them if you want to control lines.
Day 90Adults
Most livebearers are grown and can breed at about 3 months.

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

Simulator: guided

Stage 1 of 5Pregnancy

A dark 'gravid spot' grows behind the belly. Gestation is usually about 4 weeks.

Simulator: try it yourself

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

Temperature: 28 °C

Condition with live or frozen foodBig, cool water changePlants, mops or a breeding boxMove the mother after birth

About 5 young raised15% of fry survived

The female gave birth.
With no plants or breeding box, the adults ate most of the fry.

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