Neon Tetra Back Fin Loss After Fungal

[ewcia232]

I need advice what to do with one of my fish. I had my water tested in aquatic shop last week and everything is fine. The tank has been set up for nearly 2 years. I do 20% water changes weekly. Never had any problems. Week ago I bought 3 neon tetras and 3 white spot tetras. Unfortunately white spot tetras were bullying neons and nipping them and shop agreed to take them back. Day later I spotted white cotton looking thing on 2 of neons back fins. Fins were nearly gone. I bought a medication for fungal and it helped. One fish recovered completely but back fin is gone. The other one, even though fungal is gone is kinda floating in the tank, lost a bit of colour. It can't swim properly just floating head down, not moving a lot. It's been like that few days, I thought the fish was dying... I just don't want it to suffer, don't know is it better to wait and see or humanly euthanize the poor fella, I know it sounds horrible but I don't want it to suffer. Is there any chance fish will recover? Other fish I have in my 46 litre tank is panda corydoras and guppies. Thank you for any help. 
 
If photo of the fish will be needed I can upload it.
 
Thanks

 

[BettaBettas]

yea a photo would be a great help, and there's always a chance for a fish to recover, I wouldn't euthanize it. to me that's giving up. if you need any other advice just ask