You don't happen to have any neighbors or anyone who could, er, do it? I don't blame you, I don't think I could do it either. It sounds like the horrible flesh-eating thing Silverfang and I were talking about. That was crazy freaky. I think your fellow just had too much against him, poor little guy. I hope the end comes quickly for him.
Iffy how? She's not showing the same symptoms is she? For now, make sure you sterilise your hands and equipment and anything that you used with the sick guy before you use it with any other fish or turtle. Rinse everything in very, very hot water (or as hot as your hands can take) That way you won't cross-contaminate. Ah, but I'm sure you knew that already.
No, not the same. It was Cleo, she seemed to have some stringy white stuff on her. Fearing the worst I took her out of the cup from the sorority. I put her in her own jar with salted water. I can't see the stringy things anymore so I'm hoping it was just her being stressed and her slime coating wearing off. I'll keep an eye on her too though. I knew that but it is always good to be reminded right
I remember a while back we had something like you're describing. I searched for it and found it. Someone in that thread linked to something called fur coat syndrome, which I'd never heard of before. Here's a link to the old thread. I remember at the time we thought it was chemical burns from salt because we'd never seen a fish turn brown like that before.
"Fur Coat Syndrome" is a dermal bacterial infection (though most fishkeepers would consider it a fungus because it looks fuzzy). Bettas are very susceptible to this ailment, though other anaboitoids or labyrinth fish could catch it (it does not seem to affect unrelated fish).
It is generally characterized by discoloration of tissue, particularly the fins, to a dark brown or black and a grey or brown 'fur' or mold over the body, usually starting across the back and at the base of the fins and rapidly spreading to cover most of the body.
Loss of appetite and listlessness are also common signs. Though this disease can be readily prevented by keeping your Betta in warm enough water, providing them with a good diet, and setting them up with enough space (not keeping them in a bowl or vase), it is highly contagious, and can be spread through the air over 100 yards (possibly more).
"Fur coat syndrome" is almost always fatal within 30 hours of the first signs or symptoms. In cases where you know that one fish has caught this disease, using a targeted Betta antibiotic can reduce the risk of contagion to other fish. This is why the Betta water in many pet stores is often dark blue or green in color - shipping is very stressful to the fish, and often, even under the best care, the fish will drop below 74° Fahrenheit while shipping, making them very susceptible to this disease, and keeping them in a targeted antibiotic solution greatly increases the fish's survival rate in the face of this illness.