Recently I lifted the water dishes (which are at the coolest, shallowest part of the tank with aq. gravel beneath) and discovered in the gravel, which has a tiny pool of salt water from spills, the following: a tiny creature, about 1/16" with what appeared to be a 3-segment body, almost transparent, with about 6-8 tiny flippers and dark spot of front; more or less swimming/paddling in the water around gravel. I've heard and read about a lot of different kinds of parasites, but never anything like this! Nothing like a maggoty-type worm or water-type bug. As far as I know, it's still there, in the water around the gravel; doesn't seem to affect hermies.