What is Medaka?

The medaka is an endemic species that has lived in the Japanese countryside, streams and ponds since ancient times. The wild species is dark brown and varies slightly in colour from region to region. They are very adaptable and can survive on very little water, but during the period of high economic growth, environmental degradation of streams and ponds and excessive use of pesticides in the countryside led to a sharp decline in their numbers. They were also driven out by the caddisfly, introduced from abroad to control mosquitoes, and are now confined to relatively cold-water areas in the mountains.

In recent years, however, medaka numbers have gradually recovered in some areas as a result of environmental improvements and conservation efforts. In addition, medaka bred for ornamental purposes are readily available in pet shops, and the Yang Gui medaka, for example, is easy to breed and sell in large quantities. It is popular as a fish that can be easily kept on the veranda of a house or on the balcony of an apartment complex.

History of the medaka

The medaka's name comes simply from its appearance, with its eyes held high. The name varies from region to region, but it seems that the name "medaka" spread from Edo (Tokyo).

It is believed that the appreciation of medaka began around the 18th century. The water bowl was covered with gravel to keep the water shallow for the medaka to swim in. Just as people today are fascinated by the adorable appearance of medaka swimming in a water lily bowl, people in the past enjoyed watching them swim from above.

In the 19th century, the appreciation of goldfish became the norm and the practice of medaka appreciation declined. Goldfish are vibrant and spectacularly coloured, so it is perhaps inevitable that the popularity of the dull medaka has declined.

At the turn of the 20th century, the number of people who appreciated tropical fish increased. After the war, when many tropical fish were imported from overseas, equipment was developed for breeding them and this led to an immediate boom in tropical fish. However, the humble medaka were not popular.

At the turn of the 21st century, the popularity of medaka increased again. This is because medaka with bright reds like Queen Yang and medaka with shiny backs like Miyuki were created, and medaka with the beauty of a tropical fish began to circulate. The low cost of keeping medaka compared to tropical fish and the fact that they are hardy are also thought to be reasons for their popularity.

How can I tell a male from a female?

Males and females Males and females differ in the shape of their dorsal fins. While the male's dorsal fin is diamond-shaped, the female's dorsal fin is narrower towards the back.

There is also a difference in the dorsal fin, with males having an elongated dorsal fin and females having a rounded dorsal fin.

During the egg-laying season, females have a thicker body and males are more intelligent, so it's easy to tell them apart from the top. To some extent you can tell if it's male or female by looking at it from above, then scooping it into an acrylic or glass case and looking at it from the side to check the shape of the fin.

Medaka love people

It is often said that when feeding the Koi in a pond, if you clap your hands before feeding them, the clapping of your hands will cause the Koi to flock to you. Is it possible to do the same with medaka?　Yes, if you make some sort of sign when you feed them, the medaka will come to the surface because they think they are being fed. Also, medaka kept in a public place will be more wary of people than medaka kept in a private place. If you keep Medaka in a public place, they won't be surprised or hide when people approach them. Instead, they will come to the surface and beg for food when people approach.

Also, if you maintain your aquarium frequently, they will come close to your hand instead of running away when you put your hand in. I can't say they're as friendly as dogs, but medaka will respond to you if you treat them with affection. A friend of mine feeds his medaka by saying, "Here's your food! The medaka will respond to this call and come to the surface. Give your Medaka lots of love and care.