Moonfish

According to i09, citing National Geographic, there is oxygen-rich water on Jupiter's ice-covered moon, Europa:

That amount of oxygen would be enough to support more than just microscopic life-forms: At least three million tons of fishlike creatures could theoretically live and breathe on Europa, said study author Richard Greenberg of the University of Arizona in Tucson.

"There's nothing saying there is life there now," said Greenberg, who presented his work last month at a meeting of the American Astronomical Society's Division for Planetary Sciences. "But we do know there are the physical conditions to support it."

In fact, based on what we know about the Jovian moon, parts of Europa's seafloor should greatly resemble the environments around Earth's deep-ocean hydrothermal vents, said deep-sea molecular ecologist Timothy Shank.

"I'd be shocked if no life existed on Europa," said Shank, of the Woods Hole Oceanographic Institution.