

What got to his back fins?
I’m worried it could be the filter? Do filters cause this kind of tearing? I haven’t added anything new but there has been some stringy algae in the tank. Photo 1 is “before”, photo 2 is “after”
Edit 1: More info on water parameters. Everything is ideal (ammonia is 0, nitrite is 0, etc.) except for pH. My pH is at 8.2.
I have been dealing with an algae bloom likely causing the high pH. I’ll do a deep clean of the tank to remove the algae and leave the tank light off for a week.
But would the high pH be causing the issue with his fins?
I’m going to watch his behavior for a bit and make sure he isn’t nipping at himself.
Edit 2: After observing his behavior for 15 minutes I did not notice any self-nipping. He is behaving normally except for 1 thing. He’s only staying in like one area of his tank and not swimming throughout all of it like usual.