About 4 days ago I noticed my goldfish's fins fraying. They've done this a couple times when the tank was first cycling, and a quick water change would fix it. The tank is fully cycled, the water is perfect, but his fins are still fraying. :/ He acts completely normal, still eats and hangs out with his buddy. I started to treat him will Melafix about 3 days ago, but I'm seeing no improvement on his fins. I'm going to keep treating him and then do a 25% water change like the bottle says, but i'm wondering if there is something else I could do to help his fins heal?