Hi! I'm new - to this board and to fish in general. I have a rag-tag team of fish that I inherited a couple months ago in a small (5 gallon) tank; a bala shark, a red-tailed shark, a pleco, and a guppy. There was also a betta in there when I received the tank, but he died several weeks later.
All was well with the remaining inhabitants until about 3 weeks ago, when I noticed the guppy was turning black. Nothing else appeared wrong with him, just the area around his lips and the back half of his body were much darker than usual. I read online that it could be a result of stress, so I started keeping a close eye on him. About 2 weeks ago he stopped eating, and he had been a voracious eater before that. At first I thought it was Velvet (I thought I saw a vaguely yellowish patch behind his fin, and I caught him rubbing once on a rock) and treated with Quick-Cure for a week. Another week has now passed, and my poor guppy is still black, and will eat neither flakes nor brine shrimp that I provide. He has no sores, patches, or strange behavior that I can perceive (yellowish spot still there, but I think maybe it always was and I'm just paranoid), he still swims around normally. I also thought he might be constipated, but I've seen him poop twice, though it was kind of white and stringy.
I've done some searching and the only thing that seems to match his symptoms is hexamita. (from this website:
http://animal-world.com/encyclo/fres...s.htm#Hexamita) But I hate to subject them to more treatment without knowing for sure what's wrong.
I'm picking up a larger (20 gallon) tank tomorrow, but I'm kind of hesitant to change these sick fishies' environment. Any ideas what may cause lack of appetite and color change and what I can do to help him (and keep his tankmates from getting sick)? I'll attach a picture, in case a visual aid helps.
Thanks!