That happened to one of my big boy gups. I was cleaning the tank and my mom said she had seen a guppy laying around on the floor right where my vacuum was, then after a few minutes i found him swimming OK, but with a litle fin rot and the scales were starting to stand up. I didn't expect him to live very long, but I let him die in a small private tank. It only took a few hours, even though I gave him some melafix and extra strss coat and was thinking about what I might add next. Now I only have 2 boys left with delta tails. I think i had about a hundred a year ago. but I didn't count and most were not very big yet. I probably really had fewer than 50, but I thought I would have more for longer.