Things to prepare before buying Medaka (Rice Fish)

Things to prepare before buying Medaka (Rice Fish)

There are things to prepare before starting the breeding of medaka. Because you deal with life, you should prepare the minimum necessary items before you buy Medaka.

You need to prepare a container (water tank), bottom sand, aquatic plants, bait, nets, buckets, chlorine remover, and lighting equipment for indoor breeding, before buying medaka.

Container (water tank)

It is said to require about 1 liter of water per one medaka. However, this is a standard, and if the condition of water is stable, even 3 to 4 medaka can be bred enough in 1L. It is ideal to use bottom sand and aquatic plants to stabilize the water condition.

Containers include water lily pots, Styrofoam boxes, plastic water tanks and glass water tanks. For outdoor rearing, water lily pots and foam containers with small changes in water temperature are suitable. For indoor rearing, we recommend glass aquariums that can be observed from the side.

A large container is suitable because the larger the amount of water, the easier it is to stabilize, and the change in water temperature is small. However, when rearing indoors in a glass tank, the weight of the water is so large that a firm water tank stand is also required.

If you enjoy the aquarium, we recommend glass aquarium rather than plastic aquarium. The plastic tank is easily scratched, and it becomes white and cloudy and you can not see inside well.

Bottom sand

We recommend that you lay sand on the bottom of the tank. It is possible to breed without it, but bottom sand is the best way to keep the water clean.

In the medaka tank, toxic ammonia accumulates due to medaka excrement and leftovers of food. The more water the microbe in the tank breaks down the ammonia, the more stable the water and the health of the medaka is maintained.

Many microorganisms live in the bottom sand. Bottom sand is essential to maintain many microbes.

There are many types of bottom sand, including sand, gravel, and soil. Wash sand and gravel well before using. There is no need to wash the soil.

Water plants

Water plants are not always necessary, but are items that contribute to stabilizing the water. The presence of aquatic plants makes it easier for microorganisms to cleanse water, and aquatic plants also have the ability to clean water like microorganisms.

Water plants decompose carbon dioxide emitted by medaka and produce oxygen. The more oxygen there is, the less medaka gets sick and it grows better.

In addition, aquatic plants look beautiful and have a healing effect. Green carpets and water plants that grow like a forest are very relaxing. Medaka also settles in a tank full of green rather than an empty tank.


Because medaka is a living thing, feeding is essential. We recommend the bait floating in water, which is sold at home centers and pet stores. Medaka like to eat food on the water. With floating food, the amount of leftovers decreases and it is easy to maintain the water quality.

There are many types of food for medaka, and there are good ones to give during the spawning season and good ones during the growth season.

Pay particular attention to the size of the medaka and the size of the bait. If it is a juvenile fish, it still need bait for juveniles fish, and it needs also a small but nutritious diet, especially for the growing season.

For adult fish, it is also effective to change the feed at the spawning season and at other times, but it may be cheaper at home centers.

In addition, at the time of breeding, because food for breeding is also sold at home centers etc., I would like to use it well.


You also need a small net to scoop the medaka. It is not recommended to put the pet shop water directly into the tank when putting the newly bought Medaka into the breeding tank. A small net is essential so that you can scoop only the medaka and transfer it to the tank.

In addition, we need a net to isolate sick Medaka and to scoop unfortunately dead Medaka.


A bucket is essential to change the water in the tank. If possible, prepare two buckets. At the time of water change, it is necessary to have a bucket to keep the temperature in advance and to make the water dechlorinated, and a bucket to put the water taken out of the breeding water tank.

In the water change, about 1/3 of the water in the tank is changed, but if you put too cold water, medaka will become ill. Also, if you add water containing chlorine, medaka will die.

Chlorine remover

In the case of tap water, the water contains chlorine for sterilization. This water with chlorine in it is poisonous to medaka.

There are two ways to remove chlorine from tap water. One is a method to store tap water for half a day. Chlorine is released into the air with time. If you leave it for half a day, chlorine will disappear.

Another way is to use a chlorine remover. There is no need to store it and chlorine can be drained from tap water immediately.

Lighting equipment

Lighting equipment is necessary for the growth of aquatic plants and the health maintenance of medaka. Medaka grows in health by being exposed to light. In addition, by adjusting the time to keep the light on, you can encourage egg laying by making the medaka feel as if there are four seasons indoors.

Lighting equipment is fine with LED lights that are cheap for electricity. It may be a water tank or a clip light. If you want to grow aquatic plants, we recommend using a tank light. Clip lights can replace bulbs, but are not suitable for illuminating a wide range. If you use a tank of 30cm or more, please use the tank light.

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