I don't have a picture but you can't mistake them. They look like little black beetles (easiest descriptor - shiny black in color). You usually see them moving around the snakes eyes and head. When you smash them they have lots of blood in them.

You typically don't see just one you see several.

If what you found in the water doesn't clearly look like a bug then it most likely wasn't a mite. But I agree coming from a bad home you have no idea what it has...safest way is to just go ahead and treat him assuming he has them (the treatment will kill anything else that might be hiding).

Go online and purchase some Provent-A-Mite (aka PAM) follow the directions exactly as they appear on the can and your worries are over.

Hope this helps