My tiger barbs are mean, I wouldn't put something with long fins in there with them. I recently added two kissing gouramis and a BN pleco. The gouramis (despite being twice their size) were being harassed by the barbs. That was the first day, now the barbs seem to leave them alone for the most part. There's a little chasing, but not nearly as bad as it was the first day. Now the shoal moves for a gourami, unlike when they were being harassed.
On a lighter note, the pleco hasn't been bothered, although he says hidden most of the time.
I love my barbs though. If my gouramis top out too big for my 55, I'll probably make it all barbs with the BN pleco for clean up.