3 simple tips to increase the hatchability of Medaka eggs.

Hatching Medaka eggs is much easier than hatching other ornamental fish eggs, and the hatch rate is very high. Anyone can hatch Medaka eggs by following these three simple steps.

1. keep the water clean

This is the most important rule for proper egg hatching. The most common cause of hatching failure is mould that develops on the eggs. Fertilised eggs are clear in the early stages and as they develop you can see the medaka's eyes, but unfertilised or dead eggs are cloudy. If left unattended, these dead eggs or food scraps can become a source of fungus and inhibit the healthy development of the eggs.

Place the eggs and about 2cm of water in a plastic cup. The water should be tap water, not culture water. Tap water with just the right amount of chlorine will prevent the growth of bacteria. If you want to make it even cleaner, you can use diluted methylene blue. The water level should not be too high so that the surface area of the water is large and the eggs are well oxygenated. Replace the water with fresh water every few days.

2. Total water temperature of 250°C

A total water temperature of 250°C is required for Medaka eggs to hatch.

For example, if the water temperature is 25°C, the eggs will hatch in 10 days (250°C divided by 25°C); if the water temperature is 20°C, the eggs will hatch in 12.5 days (250°C divided by 20°C).

All our eggs are delivered after cell division has been confirmed, so they are already 3-7 days old. If the eggs are received and kept at 20°C they will hatch in a few days to a week.

If the water temperature is below 15°C, the eggs will develop much more slowly and are more likely to become mouldy. The ideal temperature is between 20°C and 26°C, so even if the water is kept at room temperature, it should be kept as warm as possible.

3. Daily observation

No matter how well you prepare the environment, you are dealing with nature and there are many factors that can cause the eggs not to hatch. You don't have to do this every day, but you should check the eggs frequently to make sure they are not dead and that they are developing properly.

If you look closely, you can even see the heartbeat and blood flow. If the eggs are close to hatching, they will start to spin frequently. Tap water should be free of lime by the time the fry hatch, but be careful to change the water just before they are born.

Newborn fry do not need to be fed for a few days as they absorb nutrients from the yolk sacs. They are not yet able to swim, so aeration should be avoided as much as possible.