Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Ditto, and even if it tests OK, do a water change, anyway, emphasizing vacuuming the floor of the tank.
I am not sure Melafix is the best for a Labyrinth fish.
Clamped fins (tail or other) suggest there is a problem, but not what it is.
Body losing color might just be because he does not feel good. Still, I do not know what it is.
How long have you had him, and what are the water parameters?