It sounds like you may both be nervous and animals may sense this. You can put a T-shirt in his cage that you have worm and that will introduce him to your smell. You can then put your hand in the tank after he has had a couple of days with the shirt and work your way up yo getting closer and closer to each other. Take your time. I have never been bitten by a ball but I have been bitten by some other species. Obviously it depends on size and species but it didn't hurt. Had I not seen it happen I wouldbt have known. I don't know if this is the case with bps. If he does bite try not to pull your hand away. You don't want to hurt him. Even if it does hurt it is not as bad as it seams and I promise worse pain exsites. It is not probably crying level pain. But in conclusion give yourself time and worm at the pace you feel comfortable.
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