I am looking for ideas on what everyone things could be causing this. Monet is kept in a 2.5 gallon planted tank with crypt wendtii, spiralis and a few sprigs of purple cabomba. It has been up and running for over a month and is cycled. I tested today and it is 8.2 ph, 0 ammonia, 0 nitrate and maybe about 1 ppm nitrate if that (first and second colors are 0-5 so I'm not quite sure where it falls, but looks very yellow/0). I had a problem with hair algae so I had been doing a 50% water change and dosing with about 0.5 ml Flourish Excel every 2-3 days and that seems to have gotten things cleared up. I have a sponge over the intake. He lives by himself or a few cherry shrimp before he gets around to eating them. Some of the plant tips of the spiralis look a little brown and pokey - could that be hurting him? He throws himself through the foliage in chase of shrimps (or pretend shrimps) and really isn't very gentle on himself. He sometimes rests against the sponge of the filter, but it has a very gentle suction and I have it on low-medium at all times (Azoo Palm). You can see from the photos most of the shredding is to his back fins and towards the back of his bottom fin.
Any ideas on what could be causing this???
He is my baby, I want him to be happy, healthy and as gorgeous as when I first got him...