HI everyone. I was worried about the dorsal fin of one of my plecos which seemed torn in places (in the soft tissue between each spine). No sign of fin rot/changed behaviour/changed colour. Just seemed like mechanical damage, but I'd never witnessed any fight (still possible that it happens at night, but very unlikely, as my plecos really seem to get on). After one of my numerous visits to one of my numerous LFSs, the guy (pleco specialist) said that when they get startled, they will snap their sail open, which will cause tears. He says it just grows back. Interesting, interesting!