I'm hoping some of you much more knowledgeable fish keepers can help me. I have a guppy that has spent the last week sitting on the bottom of the tank barely moving and seeming to be breathing very heavily. He's barely been eating but will frantically try to get to some bits of food as they go past when he notices them. I've tried giving him sinking pellets but he doesn't seem able to tip himself to nibble at them. I've tried giving him finely crumbled flake as close to him as I can get without panicking him but he ignores it after the first mouthful or two. I transferred him and another of his tank mates into a separate quarantine tank when I noticed this behaviour in both of them. I bought some all-round medication for bacteria/fin rot/ulcers etc and have dosed according to instructions for the last 5 days as per my advice from my LFS. Did a 75% water change before starting medication. The other sick guppy died after a couple of days but this little guy is still hanging on but not improving. Does anyone have any advice as to what it may be and how to treat it? If he's unlikely to recover can anyone recommend the dosage for clove oil to euthanize him? I'd rather he wasn't suffering or starving to death. Bit of tank info: Both were bought from my LFS about 6 months ago. The main tank is a 125 litre planted tank with a sand substrate that has been running fine for over 6 months. Recently added some zebra danios, new guppies, glowlight tetras and pentazonas (about 5 of each) Older tank mates are a couple of guppies, some neon tetras, a pair of julii corys and a pair of bristlenose plecos. Quarantine tank he is now in is a 40 litre with a sand substrate that I was just about to finish setting up as a shrimp breeding tank after it finished cycling. Both tanks have 0 ammonia and 0 nitrite 5 nitrate. The big tank had higher than that but a water change sorted it out without any recurring problems.