Breeding medaka indoors in the dead of winter in a Medaka Aqua One

Outside, it is dark and the garden is asleep. In the living room, a small aquarium remains lit. This morning, on the strands of the spawning mop, you thought you saw a speck of dust. Up close, it was no dust: it was an egg, tiny, clinging there while everyone slept.

A few days later, in the basket floating on the surface, something moves. A fish that was not there yesterday.

Yes, you can breed Medakas indoors, even in the middle of winter. In the garden, the season decides. In the living room, you control the temperature and the light. Spawning is never guaranteed, as it depends on the age of the fish, their health, and the ratio of males to females, and the juveniles must first grow up. But the path is clear, and here is how to follow it in a Medaka Aqua One.

Why winter no longer decides

In Japan as with us, the life of an outdoor bowl follows the sky. When the water cools and the days shorten, nothing pushes the Medakas to spawn. It is not due to a calendar: it is due to two conditions, the warmth of the water and the duration of the light.

However, these two conditions, an aquarium puts them in your hands. Once the water has the right temperature and the day has the right duration, January looks like a beautiful season for your fish. That is the whole mechanism, and it explains why winter becomes the best time to start: you have time to watch.

Heat and light: the benchmarks to aim for

Temperature

No heating is necessary to keep Medakas. It serves another purpose here: aim for a rearing temperature when the season does not offer it. The manufacturer indicates that Medakas reproduce from 15 °C, ideally 20 °C. Hikari indicates 24 to 28 °C for rearing. These benchmarks do not contradict each other: the first says when spawning becomes possible, the second where to aim for warm rearing. All remain in the 10 to 28 °C zone recommended by our supplier.

In 25 liters, a 25 W heater and a thermometer to stick on the glass are enough to follow this at a glance. Look at the thermometer every day: it is it, and not the setting, that tells you the truth.

Light

You need at least 13 hours of light per day. The Medaka Aqua One timer offers 3, 9, or 12 hours. Choose 12 hours and let the room light do the rest: the evening in the living room naturally completes the day of your fish.

A group ready to spawn

Healthy fish and a balanced group, for example 2 males for 3 to 4 females: that is the basis. The adult Medaka measures 3.5 to 4 cm. Juveniles of 2 to 3 cm must first grow and settle. Six young fish do not guarantee the ratio between males and females either. This time is not a waste. You learn to recognize your fish, and one morning, two fins tell you who is who.

The steps, from the spawning mop to the basket

1. Install a gentle current. A strong current forces the Medakas to swim too much and exhausts their energy. A very gentle air filter, like the Medaka Filter Kit, is well suited.
2. Set heat and light. Check the thermometer, then the duration of the day.
3. Switch to Hikari Breed. This protein-rich food starts above 20 °C.
4. Place the spawning mop. The Spawning Mop floats, imitates plants and attracts spawning. Plants also offer a support.
5. Observe every day. Look for tiny eggs clinging to the strands.
6. Keep the eggs safe. Place them in the Breeding Basket, or move the whole mop into a separate container.

When spawning starts, the manufacturer indicates 10 to 20 eggs per day for about 20 days, with hatching in 4 to 10 days. Take these numbers as benchmarks: your fish will have their own rhythm, and that is exactly what makes every morning interesting.

What the breeding basket does

Adults can eat the eggs and the fry. The Breeding Basket, 13 cm in diameter for 7 cm high, floats in the aquarium and solves this problem with elegance: its ultra-fine mesh protects the eggs and the newborns while allowing water to circulate. Its floating ring is removable for cleaning.

Feeding the adults, then the fry

Hikari Breed feeds the adults: it is rich in protein and floats, which suits a fish that swims near the surface. For the newborns, switch to Hikari Baby, in very small granules, 2 times a day, which is eaten quickly. Remove the excess. For adults as for the little ones, the rule does not change: small portions, because overfeeding harms the water. Hikari Next, floating growth food, will then take over for the young.

The first weeks of the fry

After hatching, the water quality can deteriorate quickly, because of the remaining eggshells. This is the most delicate, and most beautiful moment. Watch the water closely and make partial changes if necessary, making sure not to suck up eggs or fry.

For routine maintenance, change about 10% of the water every 1 to 2 weeks, with Medaka Care. The manufacturer also recommends his bacteria Medaka PSB to maintain good water quality and support reproduction.

The young are small and fragile. Keep them away from the adults until they are at least 8 weeks old: first in the basket, then in a separate container when the basket becomes narrow. A small Medaka Bowl 420 or a clean container is suitable, washed with tap water and never with detergent. After growing up in the heat, they can reach 2 to 3 cm in about 3 months. For the detail of these stages, read our article from eggs to the first fry.

A lineage that continues, year after year

A Medaka lives about 3 years, and it can offer little ones every year. In other words, this group can be the only one you welcome: the young take over the place of the old, generation after generation. The fish you look at in three winters will perhaps be the grandson of the one swimming today.

With children, this story tells itself. An adult always accompanies the gestures, and it is up to them to handle eggs and fry; the children, they watch, count, and write down. The observation notebook from our article on the family aquarium finds all its meaning here.

And when spring returns, the story will leave the house. Your Medakas can join a bowl or a mini-pond, gradually: we explain how to you in the first outdoor spawns. If you are still discovering this fish, start by knowing everything about the rice fish.

Everything together in a single pack

To prevent you from looking for each piece, we have gathered this journey in the Indoor Medaka Breeding Pack: the Medaka Aqua One 25 L, the Colombo Medaka Filter Kit, the SF Eco Heater 25 W, the 20-34 °C stick-on thermometer, the Black Crystal gravel 4 kg, the Spawning Mop, the Breeding Basket, Hikari Breed, Hikari Baby, Medaka Care, three plants (Syngonium, Vallisneria and cornifle) and 6 Yellow Medakas of 2 to 3 cm, provided by Aquifarm in Nodebais.

This pack contains live fish: it is delivered only locally, by our team, in a radius of 150 km around Nodebais. The fish are young, let them grow: it is the beginning of the story.

Frequently asked questions

Can you really breed Medakas indoors in winter?

Yes. Indoors, you control the temperature and the light, so the season no longer decides. Spawning is still not guaranteed: it depends on the age of the fish, their health, and the ratio between males and females.

What temperature for Medaka spawning indoors?

The manufacturer indicates spawning from 15 °C, ideally 20 °C. Hikari indicates 24 to 28 °C for rearing. The first benchmark says when spawning becomes possible, the second where to aim for warm rearing.

Is a heater necessary to keep Medakas?

No. No heating is necessary to keep Medakas. The heater serves to aim for a rearing temperature in winter.

How many hours of light are needed?

At least 13 hours per day. The Medaka Aqua One timer goes up to 12 hours: complete with the room light.

How long before hatching, and when to bring the young together with the adults?

The eggs hatch in 4 to 10 days. Then keep the young away from the adults until they are at least 8 weeks old, because the adults can eat the eggs and the fry.

Read also

• First Medaka spawns in spring: bowl or mini-pond
• Rice fish: everything about the Japanese rice fish (Medaka)
• Medaka reproduction: from eggs to the first fry
• Medaka: the complete guide to start well
• This winter, offer your children a little world to keep alive
• Daruma, Miyuki, Lame: understanding Medaka varieties