The tiny cichlids will be carried by a 25-foot-long rocket more than 160 miles above the Earth's surface, The Local reported. Liftoff is scheduled for next week from the Esrange Space Center in Kiruna, Sweden, an iron-mining town above the Arctic Circle.

The fish will spend about 6 minutes weightless during the trip.

"Quite simply, they are going to be seasick until they have managed to acclimatize," said Johanna Bergstrom-Roos, a spokeswoman for the space center.

Once the fish are back on Earth, German researchers will examine their otoliths, structures in the ear that sense changes in acceleration. The scientists are testing a thesis that otolith structure may determine how sensitive a human -- or a fish -- is to motion sickness.