Hey guys.

I thought my crisis was over at last: the tank had safely gone down to a very acceptable 77F. However, woke up this morning and thought I had lost one of the guppies: she was just laying on the bottom and the others were shoving her. She is alive though: swam off to hide when I turned the light on. But something is definitly wrong.

She is the fish I was concerned about last week cause of her behaviour. She seemed to be doing ok but today she can't swim properly. I quickly saw why: her dorsal and tail fins seem to be "stuck" together. Like clamped as if they were glued. I immediatly put her in an isolation tank (Those breeder box thingies) so the others wouldn't damage her. Other than being slightly white and her fins are clamped, she looks ok. I am looking at her now while writting, and it looks like there's this sort of white "coat" covering her back from the fin to the tail.

Any ideas what's wrong? Is it like fungus or something? What can I do? :unsure:

It is either a fungal or bacterial infection. It could be columnaris which is a bacterial infection with white patches. Fungal infections are usually a fuzzy white. I would treat her with antibiotics that say they cure columnaris. Also, add aquarium salt (a tablespoon per gallon) and MelaFix (natural antibiotic). It's strange that her fins would be stuck together; that would seem to indicate that strands of fungus were holding them together. You might as well treat with a fungus medication as well. Since she's in quarantine (I'm assuming the water isn't shared; if it is, then be careful with medications), you don't have to worry about dosing the other fish with too many things at once but sometimes it's needed for a fish in such dire condition. I hope she beats the odds and recovers!