If you think he's in trouble. Take him to a vet. Yahoo Answers is not a vet and asking strangers from the internet is not a good way to go. It's common sense. If you're having a heart attack, would you ask Yahoo Answers for symptoms of heart attacks?

its dangerous but if u feel he/she acting weird take him/her to a vet :)

He bit the closed chocolate and tore its cover and throw the piece he had picked with his bite already , I guess he just tasted it not even eating ,but its scaring me , will it be toxic for him ?

Thank you.