Hi all, we have had a small 12L tank for about 3 years, started with 5 WCMM but after about 18 mths, over a period of about 6mths, one by one they started getting skinny with fins down, floating at top or bottom, then dying. Usually over a period of 2-3 days and water change didn’t help. We can’t get WCMM where we are any more so I got 2 leopard danios but they chased the WCMM all the time. We have one left and he seemed happy enough, I know they like company but pet shop didn’t have anything I thought would be suitable tank mate just yet. Anyway he started going to same way as the others - fins down, staying at top of water, not eating - and after lots of research, water changes, broad spectrum treatments etc he seemed to be getting better but 2 weeks ago I did a quick water change and the next day he was on his side at the bottom. I did stir up the gravel a bit to net out the waste, but he’s been fine with this before. I’ve now tried multiple small water changes, ammo lock, 7 days of stabiliser, and aquarium salts in case it’s a parasite and not ammonia poisoning, but he’s no better, not eating, bloated, pale, pine coning and eyes all goggly. Should I euthanise him? I have clove oil. I really want to save him but if he’s past it I don’t want him to suffer. Thanks for your help.