He's starting to bite!!!

Yesterday I was told by one of the carers that my LO kept trying to take a bite out of the other bubs! :redface:

Since he has started at childcare he has been the victim of a serial biter(s) - I've lost count of the number of forms I've signed because of them, some have been quite serious with marks lasting for days as they almost broke the skin (thankfully none thus far have!).

My concern now is that he's learnt that biting is "fun". Any tips on what I should do? He doesn't bite as such at home - when he has tried it's been more of "mouthing" if that makes sense? Their policy on biting clearly didn't work when he was the bitee, now I'm worried that it won't work for him as the biter.