Breeding Platinum Medakas

Medaka or Ricefish (Oryzias latipes) as they are commonly known are native to Japan, China and Korea.

Medakas are found in slow moving streams in the wild but have flourished in rice paddies which provide excellent habitat for them to breed.

Medakas have become very popular in the aquarium hobby because of their tolerance to a wide range of temperatures.

They can happily live in water temperatures between 5 and 30 degrees Celsius.

As such Medakas are kept and bred by hobbyists in aquariums and outdoor ponds all over the world.

Many colour morphs have been bred by professional aquarists and some command very high prices.

The platinum medaka is a beautiful colour morph which is now readily available in Australia for around $10 per fish.

I bought 6 platinum Medakas from my local aquarium in early 2023 which placed in a 60 litre aquarium to condition them up ready for breeding.

The sexes are easily told apart by looking at the shape of the adult fish.

As adults the males are slimmer and more colourful than the females which are larger and have more rounded bodies.

When my platinum Medakas were ready to breed I placed them into a smaller 20 litre tropical aquarium filled with aquatic plants.

It didn't take long until I saw the female Medakas carrying eggs on their anal fins.

Medaks are egglayers whereby the female lays eggs which adhere to the anal fin and are then fertilised by the male.

After fertilisation the female swims around and finds a safe place to deposit the eggs.

I left my platinum Medakas in the breeding aquarium for a week then I removed them to allow the eggs to hatch.

Medaka eggs take about 3 weeks to hatch and once hatched the fry can be fed on infusoria and fry powder.

In 6 months the medaka fry are sexually mature.

My platinum Medakas produced around 30 fry which I raised to adults quite easily on microworms first then powdered dry food.

In summer I moved these young fish into my outdoor pond where they are now old enough to breed.

I have been feeding my platinum Medakas in the pond on dry and frozen food and making regular water changes.

The pond temperature over summer has been around 20 degrees Celsius, the pH neutral and TDS at 150 which is my local tap water.

I have placed spawning mops in the pond to encourage the females to deposit eggs in them.

Medaka eggs are quite large and can be readily seen on the spawning mops.

I have been removing the spawning mops with eggs to another outdoor pond for hatching as I found that the adult Medakas tend to eat the newly hatched fry if they are left together.

Using this method I already have another batch of young platinum Medakas growing up nicely.

I will leave my platinum Medakas in the pond year round now and of course I won't expect any breeding activity over the winter months as the water temperature will drop to below 10 degrees Celsius in my area over winter.

The platinum Medaka is an inexpensive, undemanding, easily bred and beautifully coloured fish to keep and breed and I would recommend them to any one for the home aquarium or outdoor pond.