This is my bristle nose pleco fish, Fanta, I got him a bit more then two months ago and when i got him his fin was a bit black at the top and a month ago i thought it was finrot so i used fin rot treatment but it wasn't going away. I dont see much of a dificulty of him swimming but recently i saw he also have some black on one of his side fins. If any of you guys know what this is or if you guys know how to treat it please tell me ?