How to Find and Kill Evil Hitchhikers

[Matt]

I'm going to chime in on the "not a hitch-hiker" theme. Any such deaths (crabs, mantis, bristleworm, etc) should be a predatory act, and should leave signs of that.

Red, puffy gills are a sign of a number of things I've never seen in my personal experience, including parasitic infection, introduced chemical irritants (including "hot" changewater, ammonia, chlorine, etc), overdosing with additives, heavy metals (unlikely here due to the relative effects on the inverts), bacterial infections, solvents (recent home renos, painting, etc?).

If it just started happening, it is likely something you did, or your water supplier did.

[jslaney]

I remember reading a post about killer pods. Not sure if that could be it but from what I read they were incredibly nasty. Anyone remember where that link is?

It talked about a diver encountering them in the ocean and having his face attacked. Apparently they show up in aquariums on occasion.

Good luck.