Maybe the fish have been caught in a deprived oxygen environment, and then died of fresh water?

It is not effective in an oxygen deficient environment or against ammonia.

In a low oxygen environment, it would be rather easy to build up large quantities and find yourself debilitated by pain.

His lungs are handling the transition to an oxygen environment quite well.

Some species have adapted to living in different oxygen environments to accommodate those variations.

Both types require an oxygen free environment inside the lamp.

When trees and plants died, they didn't really decompose in the low oxygen environment.

And a silicon-based life form like this probably couldn't exist in an oxygen environment.

This is to compensate for perpetual low oxygen environment.

This is due to the cold temperatures and low oxygen environment these butterflies live in.