No... You cannot bring them back to Hong Kong at all... Neither hand-carry or check-in luggages...
As crab are forbidden to be carried unless you have notifly the relevant airlines and also the crab have medical documents suggesting that they are safe to bring back to Hong Kong...
But it would take weeks for you to get all the revelant documents in order to bring your crab home... So I would suggest you not to bring any...
However, you can always try to smuggle them through with your check-in luggages... But I am not suggesting you to do so as it if you are found with crab without the relevant documents, you will be in deep trouble...