MEDAKA KEEPING TIPS

Medaka fish are omnivorous and will eat a wide variety of foods, including plankton, daphnia, dander, plants and small insects, as well as the eggs and fry they lay. If you wish to keep them at home, we recommend using commercially available ornamental fish food.

Medaka have an upward-facing mouth, so they will eat food that floats to the surface. If you want to feed the fry, crush the food into pieces that will fit in their mouths.

Medaka can be kept outdoors as easily as carp and other fish. However, killifish can be easily bred and propagated outdoors in the same way as Koi fish, and can be viewed side-by-side in an indoor aquarium with tropical fish, or outdoors in a natural environment with beautiful Medaka fish.

Medaka fish can survive in water temperatures between 0°C and 38°C. However, they will not be active below 15 degrees Celsius. If the surface water freezes, they will be fine, but if all the water freezes completely, they will die. To prevent the water from freezing completely, it is advisable to use a container with a depth of at least 30cm and as much water as possible.

They need to build up their food reserves before winter, so make sure they are well fed and fattened up before the temperature drops. The fry will not be able to overwinter as they will be undernourished.

This Youtube video is a beautiful record of a year in the life of a killifish breeder in Japan.

In the wild, killifish are said to live only about a year, but in captivity, where there are no natural enemies and plenty of disease-free food, they can often live for three to five years.

In the morning we check the weather, the temperature and the water temperature. Then we feed the killifish, check their health and spawning, and if they are spawning, we collect the eggs. By the end of the egg collection, both the temperature and the water temperature have risen and the eggs from the previous day begin to hatch. The hatched individuals are transferred from the small egg storage containers to the fry tanks. The weather, temperature and water temperature are then checked at regular intervals and the fry are fed again around midday. Weather, temperature and water temperature are then checked again and the fry are fed in the evening to complete the day's care. If water changes or additions are necessary, these should be made in the afternoon when spawning and egg collection are less affected. If you have a greenhouse, open it in the morning and close it in the evening.

If Medaka are kept at a generous density with plenty of water, aim for once every 1-2 weeks in summer and once every 2 weeks to 1 month in spring and autumn. If the water is heated to a constant temperature, aim for once every two weeks. If the water is low or overcrowded, the frequency should be increased from the above. In winter, water changes should be avoided as much as possible to avoid irritating the killifish, and water should only be added when the water level has dropped due to evaporation etc. Basically, 1/3 to 1/2 of the water in the tank is discarded and new water is slowly added to the tank at a suitable temperature so as not to irritate the killifish. When changing everything in a reset, the water is adjusted as when introducing a new tank and then the killifish are introduced.