I have a school of 7 tiger barbs in my 55 and they've started to nip at my pleco's fins. He's big enough to defend himself but he doesn't seem to be all that bothered but his dorsal is getting pretty ratty looking. I assumed 7 was a big enough school. Will adding more barbs get rid of the nipping? What I'm afraid of is adding more tiger barbs and the nipping getting worse because there's more of them. Thanks in advance!