No, this isn't a veiled attempt at turning the ISS into some kind of swanky bachelor pad, but rather an experiment that will study the effects of microgravity on marine life.

Specifically, researchers will examine the impacts of radiation, bone degradation, muscle atrophy and developmental biology over a three-month period. This data may improve understanding of human health in these areas back on Earth.

"We think studies on bone degradation mechanisms and muscle atrophy mechanisms are applicable to human health problems, especially for the aging society," said Nobuyoshi Fujimoto, associate senior engineer at JAXA.

Scientists will examine small, freshwater fish in orbit, starting with the Medaka fish (Oryzias latipes). Medaka are ideal specimens because they are transparent, which makes light work of observing the workings of their inner organs. They are also quick breeders, allowing the studies to examine different generations of the fish. The animal's genome is already fully sequenced, making it easy to recognises changes in their genes.

The Aquatic Habitat, or AQH, was sent into space on July 20 and will reside in the Japanese Experiment Module, also known as 'Kibo', which is Japanese for 'hope'. While water habitats have been sent into space before, this system features an improved circulation system that monitors water conditions, removes waste and improves oxygen flow.

The habitat also includes temperature control and an automatic feeding system for the fish, while day and night cycles will be simulated by LED lighting. Video cameras will stream vision of the fish back to Earth for further analysis.

"The special bacteria filter purifies waste materials, such as ammonia, so that we can keep fish for up to 90 days," said Mr Fujimoto. "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."

If space fish aren't quite cool enough for you, space frogs could be next on the agenda. The air-water interface design of the Aquatic Habitat makes it possible to house amphibious animals too.