Yes, it's the moment we've all (secretly) been waiting for: Fish In Space!

But before you go getting too excited and start asking the big questions — like: if there's a bubble in a microgravity aquarium, what happens if the fish falls into it? Let's ponder that for a minute… — it's worth pointing out that the fish aren't actually in space right now (their habitat has just been delivered to the space station) and this fishy experiment isn't just to see how fish enjoy swimming upside down, there's some serious science behind it.

Like… to see how fish enjoy swimming upside down.

From the NASA news release:

While aquariums provide a relaxing pastime for humans on Earth, recreation is not the goal behind the new Aquatic Habitat, or AQH, aboard the International Space Station. Instead, researchers will use this unique facility to look at how microgravity impacts marine life.

The un-fished (as in, there's no fish in it, yet) AHQ arrived at the ISS today at 10:34 a.m. ET when the unmanned Japanese H-II Transfer Vehicle “Kounotori 3″ berthed with the orbiting outpost. The HTV-3 is now attached to the station's Harmony module ready for the six astronauts on board to unload the supplies.

ANALYSIS: I, For One, Welcome Our New Space Butterfly Overlords

This isn't the first time marine habitats have been launched into space, although it is the first high-tech closed water circulatory system to be installed on the space station, courtesy of the Japanese space agency, JAXA. Marine habitats were flown on the shuttle missions STS-47, STS-65, and STS-90, and the AQH builds on experience with supporting fish life in low-Earth orbit. And as you might have guessed, this aquarium isn't in the same league as your household's algae-ridden goldfish bowl.

“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," said Nobuyoshi Fujimoto, associate senior engineer at JAXA's Space Environment Unitization Center. “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."

The habitat will automatically feed the fish, it has a high-tech air circulation system and climate control, plus a specimen sampling system. LEDs will simulate the day-night cycle and a webcam will provide a Big Brother-esque voyeuristic experience for scientists (and, presumably, the public) to keep an eye on the day-to-day activities of our fishy star trekkers.

To be honest, the technology behind the space marine habitat sounds more complex than the space station itself!

ANALYSIS: Space Worms Live Long and Prosper

So, what victims species of fish will have the honor of living in such luxurious digs?

Small, transparent freshwater fish called Medaka (Oryzias latipes) will be the first species to move in after the aquarium is installed inside the Japanese Experiment Module Kibo. Researchers hope to study the genetic alterations that occur during long-duration spaceflight. As the equipment is set up to support multiple generations of Medaka, the impact of microgravity and space radiation can be observed.

As mankind looks to the stars in the hope of one day becoming a true spacefaring race, we need all the help we can get. Space isn't a nice place for our physiology — muscle atrophy, bone wastage and other health issues associated with increased radiation exposure could cut our interplanetary dreams short. Also, as we live in an increasingly aging population, age-related health issues are becoming a huge concern. So studies such as these are imperative to help us find solutions to some of the most challenging biological problems not only in space, but it can be applied to everyday medical treatments.

Oh, and wondering how fish swim in microgravity will be fun to watch too — but if the space spiders are anything to go by, the fish should adapt just fine. Shame about the butterflies, though.

Images: Top: The future fishy star trekkers: Medaka (Oryzias latipes). Middle: The Aquatic Habitat (AQH) during tests on Earth. Credit: JAXA