Wow...my Guppy who died was showing six of those eight possible symptoms...
loss of appetite
fish remains in seclusion and out of site
rapid breathing (respiration)
eyes appear to be cloudy or "popping out" -- didn't see that one
fish lies on its side near bottom of aquarium
stomach of fish appears to be sunken
whittish blotches on exterior -- nope
degraded and frayed fins
No, she wasn't holding her mouth open as far as I know...why? I noticed that before developing these symptoms she got really bloated and was that was for a long time. Then out of nowhere she started dying and was gone within probably a week. Now every fish is getting bloated.
Yes, Rose, my Guppy Sunspot looks the same as Corona did right before she died--all thin and sunken in, and fraying fins.

Just she isn't laying on the bottom like Corona did--she's more floating at the top. Actually I have noticed several fish doing that--floating at the top, with their back all bent or arched. I think I read somewhere else that that can happen if they are not getting enough vitamins and you should feed veggie flakes to prevent it, but I am feeding those. Oh, this is so confusing!
I am feeding Omega One--veggie and regular tropical flakes, Marc. Would the veggie flakes be pretty much the same as spirulina flakes?...oh wait I'm pretty sure they contain spirulina. How do you soak flakes in garlic?
I think one of my problems is my high nitrates. The tank is unplanted and overstocked. I accidently overstocked it, really long story, but I was planning to move the Otos to my new 20g tank, and then I was thinking of getting a bigger tank for the livebearers, but now i've got TB so no way I'm moving any of the fish to other tanks. I don't know what I'm going to do. (the q tank is only 5 gallons so no point in moving them all there...) At least school is out thursday...after that maybe I could double water changes or something.
Wow this post is turning into a novel so I better stop here. Thanks all for the support.
Oh, one more thing, Rose--what was that Sulfa you were talking about? Any idea where to get it?