Breeding Medaka: from egg to fish

Medaka are among the easiest ornamental fish to breed – with the right tools, you can expect young fish within a few weeks. This guide will take you from egg laying to adult fish.

When do Medaka spawn?

With sufficient light (at least 12-13 hours a day) and a water temperature above 20°C, Medaka will start spawning almost continuously. The female carries the fertilized eggs under her belly for a while before depositing them – often in plants or special breeding material.

Collecting eggs

Without aid, most eggs and young fish will be eaten by the adult Medaka themselves. To prevent this, use collection material:

• Medaka Spawning Mob - a floating spawning mop that mimics the fine root structure where Medaka naturally deposit their eggs. Females actively lay eggs on it.
• Medaka Breeding Basket - a floating breeding basket that protects eggs and fragile young fish from the adult animals.

Regularly remove the Spawning Mob with eggs and place it in a separate collection container, or directly use the Breeding Basket as a protected breeding space within the main aquarium.

From egg to fry

At a water temperature of around 25°C, the eggs hatch after approximately 7 to 10 days (at lower temperatures, this takes longer). The eggs can be identified by their clear, transparent appearance with small oil droplets.

Caring for the young fish

For the first few days after hatching, the fry live off their yolk sac and do not need to be fed. Once they are free-swimming, specialized fry food is essential – their mouths are too small for regular fish food:

• Hikari Medaka No-Mai Baby - the smallest pellet size, specifically for newborn Medaka fry.
• As they grow larger? Then switch to Hikari Medaka No-Mai Next

Feed the young fish small amounts several times a day – their small digestive system cannot handle large meals.

Breeding food for the parent fish

Do you want to stimulate the spawning activity of your adult Medaka? Hikari Medaka No-Mai Breed is specially formulated to promote spawning behavior and egg production in parent fish.

When can young Medaka return to the main tank?

Wait until the young fish are large enough not to be seen as a snack by the adult fish – usually after 4 to 6 weeks, once they are clearly larger than the mouth of an adult Medaka.

Breeding color lines

Do you want to breed specifically for color (for example, maintain pure Kohaku or Panda lines)? Then keep a separate breeding tank for each color variant to prevent unwanted cross-breeding.

Questions about breeding?

Feel free to visit our store in Heinkenszand for personal advice on breeding Medaka, or ask your question via chat.