my angels took ubridge with a tiger barb when they last spawned and nipped half a tail off
Keep water clean, try to keep stress levels down (I personally dont move wounded
fish to qq as this stresses em more) and half dose of Melafix and pimafix had it sorted in a little over a week
healthy
fish usually fix fins themselves as long as water is good - I only applied the above treatment once to freshly changed water.
Hope this helps