1. Transfer the egg into a small container (preferably one no larger than 1/4 of a gallon). Slowly acclimate the eggs to tap water of similar temperature. It is recommended to use tap water, as it contains chlorine, which helps prevent fungal growth during the hatching process. Please note that not all eggs will hatch, but this method is highly effective.
   • Helpful Tips:
     • Light exposure is also necessary to increase hatching speed, so place the egg container in a well-lit area near a window or use artificial lighting.
     • If the container is too small, water can become dirty quickly, resulting in a lower survival rate.
     • Manage eggs at a water temperature of at least 68°F. Below 68°F, the hatching rate decreases. The optimal temperature is around 78.8°F, so during seasons other than summer, use a heater to maintain a suitable temperature.
2. To maintain the freshness of your eggs, replace 30% of the water in the container with new tap water every 2-3 days. This will ensure a continuous presence of chlorine to keep the eggs fresh. Over time, the methylene blue will gradually disappear, as tap water replaces it.
3. Monitor the eggs closely during the incubation period, which typically lasts 7-14 days, depending on the water temperature. Check for any signs of fungus growth or abnormal discoloration on the eggs. If you notice any affected eggs, promptly remove them to prevent potential contamination of the healthy ones. The fertilized eggs of Medaka are either colorless and transparent or slightly yellowish. Unfertilized eggs, which turn white and cloudy, do not hatch and eventually rot, becoming prone to mold growth. Use a turkey baster to remove any white/fungus eggs. If you are uncertain whether an egg is fertilized or unfertilized, gently pinch it with your finger. Fertilized eggs exhibit elasticity and cannot be crushed, whereas unfertilized eggs are easily crushed.
4. As the incubation period progresses, observe the eggs closely for any signs of development. Initially, the eggs will appear clear with a slight tint. Over time, you may notice changes in color and the development of eyespots within the eggs. These are positive signs that the embryos are developing as expected.
5. Once the eggs begin to hatch, you will notice tiny fry emerging. At this point, it’s crucial to not change the water condition. Do not change the water for the first 7-10 days after they are born, as fry are very sensitive to water changes.
6. Start feeding the newly hatched fry after 3 days. They do not need food for at least 3 days. You can feed them PSB liquid or powdered fry food, As they grow into juveniles, you can introduce freshly hatched brine shrimp and infusoria. Offer small amounts of food twice a day to ensure proper growth and nutrition, but avoid overfeeding to prevent water contamination.
7. While air aeration is not essential for medaka, if you choose to use it, do so gently to avoid disturbing the fry.

Remember, creating a stable and healthy environment during the incubation period is crucial for successful hatching of medaka eggs. By maintaining the proper temperature, monitoring water quality, and providing suitable nutrition, you can increase the chances of hatching healthy and vibrant fry.

• Light is the most crucial aspect of fry rearing. Keeping containers in sunny spots accelerates growth and decreases mortality. However, in dim places, growth is stunted and mortality increases. It’s best to raise them outdoors, but placing containers near a window is sufficient indoors. If lighting is poor, supplement with bright artificial light.
• Direct sunlight can raise the water temperature above 104°F, which is dangerous for medaka. To avoid this, create shade with screens or use white containers or transparent aquariums, which help prevent sharp temperature increases.