I have the betta since maybe 3 weeks now. At first, there was a plastic plant in the tank but I removed it and replaced it by a fabric one, but looking into it, that plant isn't that soft... I have a few rocks that are kind of sharp edged, one is quartz cristals. I just removed the plant, because it is there that the betta hangs around the most. I have never seen him around the rocks.
The gravels are round and soft because I wanted something good for the barbels of the catfish and the very little pleco.
No, I have never seen the catfish nipping at the betta, and I am glad they can be good buddies, because I love them all. I will see if the fins are getting better and if not, well I guess I will remove the rocks and put some rond polished one. Thanks a lot !