@Demigan Hehe, I kind of hoped someone would connect the dots. That happens to be my all-time favorite movie. I almost said they need a flamethrower to remove potential parasites but I figured that'd be way too on the nose.

Oh I see, it uses a balloon effect. For some reason in my head you were describing a propulsion mechanism. My bad!

Might be naive here, but wouldn't a gust of wind be all that's necessary to displace enough of the hydrogen and bring the plant downward and potentially in harm's way?

@Frank Yeah I'm never going to be in a position to inject helium into a fish's swim bladder. Can you describe what happens for the less vertebrate-inclined? :D