berghia nudibranch

Today I got a few berghia nudibranch from a fellow reefer for free at that. They only eat aptasia nothing else. If they want to live they have to eat aptasia which is good for me. I hate aptasia like Helen hates emerald crabs if not more. Has anyone used these before. I would imagine they do work well since they won't eat anything else and will breed in captivity. I haven't really come across these guys so just checking everyone's to see how they worked for others