Astronauts at the International Space Station have been given some fish to keep them company.
The school of Medaka ricefish (Oryzias sp.) are being housed in a special aquarium called The Aquatic Habitat (AQH), which has been sponsored by the Japanese Space Agency (JAXA).
This self-contained system monitors water conditions, filters wastes and ensures proper pressure and oxygen flow rates. It also provides automatic feeding for the fish, air-water interface and temperature control. LED lighting simulates day and night, and video cameras record images of the fish. There are two chambers for the fish to live in, each 15 x 7 x 7cm/6 x 2.75 x 2.75".
The ricefish are not there as pets, however. The aim is to find out how they are affected by microgravity. They are ideal specimens for the study, as their transparency means it's easy to see their organs and as scientists have all of the Medaka genome identified, it's easier to recognise any alterations to their genes, which may arise from factors such as space radiation. They also breed quickly and easily.
Nobuyoshi Fujimoto, associate senior engineer at JAXA's Space Environment Unitisation Centre said: "In order to keep water quality in good condition for the health of the fish, we had to do many tests on the filtration system, especially the bacteria filter. The special bacteria filter purifies waste materials, such as ammonia, so that we can keep fish for up to 90 days. This capability will make it possible for egg-to-egg breeding aboard station, which means up to three generations may be born in orbit. This would be a first for fish in space."
Due to the air-water interface deisign of the AQH, amphibians could be used in future studies.
You can find out more on the NASA website.
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