Crap.

About a month ago I added new fish to my tank. I'd had 2 old tetras (one shabby, one brilliant-looking) and so added about 8 other tetras to keep them company.

Two weeks ago, I lost the shabby looking tetra--not surprising, he'd been shabby for a while.

One week ago, I noticed 2 more fish were dead. I looked closely and realized that they and all my remaining fish looked like this, in varying degrees. Apparently one of the new fish brought a gift with it--ichthyophthirius, a fairly virulent parasite. Within days, all but two of my fish were dead. I bought a treatment that supposedly will take care of it, but the treatment also kills snails; since I have 2 snails who I like, and about 40 that I hate, I figured this might be a mixed blessing, and evac-ed the chocolate snails to a hospital tank before putting in the treatment. Too late for one of the remaining fish... but the other one seems relatively healthy now, 48 hours after the treatment. So I now have ONE fish. And a tank that may or may not still be infested with free-swimming parasites. And 40 snails who appear to be completely resistant to Mardel Coppersafe. God DAMN it.