my 8 month year old redtail has always been friendly,when i went to go pick him up,he hissed and just opened his mouth.im pretty scared to take him out now.what should i do?

I wonder if he could be getting ready to shed his skin and is uncomfortable.

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I would definitely recommend that if he continues to act abnormal, you should probably get him to a vet for a checkup. Good Luck!

Oh, and Welcome To AnswerPool Bryan!

before you run out to a vet you might want to consider that you probably startled it or it could be in shed. have you had it for very long? sometimes it takes a while for a snake to get used to being handled. even a "tame" snake will sometimes simply be in a bad mood. they are capable of such mood swings, you will overtime get to know your snake and sense their mood. tips for approaching your snake: do not pick up a sleeping snake (ruffle the bedding or give a little poke and let them know you are there before picking them up), do not reach towards their head, be gentle and do not make quick movements. unfortunately it may take a few nips for them to learn that you aren't a threat. wear long sleeves and gloves if necessary.