My young male cobra guppy had fun rot and I have been doing 25-50% water changes every week, I also use MELAFIX to cure the fin rot. This has been going on for about 2 months just 2 weeks ago I noticed that his tail is getting shorter and shorter, now he barley has a tail. He can swim good and is eating and even breeding with the females still, I can see it takes him more effort to swim because he is using a wiggle motion with his whole body. I can see that the fin rot is still there. He is still active and alert, I just feel bad. Any ideas on what I should do?