male columbian boa

Question
Hi.  I have a three year old male that I bough four weeks ago and two weeks ago we bought a three year old female for him as companionship.  Both are very docile.  However just over the past couple of days our male will open his mouth and hiss when we place him on the grass, and once in a while he will hiss in is tank.  He will not eat outside of his tank, and will only eat (frozen) rats when we feed him in his tank. However I have heard that this makes them agrresive.  Is this true, and why is our male all of a sudden starting to hiss?
thanks for your help.
sincerely,
Maria H

Answer
Hi Maria,
  I have fielded a lot of questions this week about aggressive snakes that are normally calm. Could be something to do with the coming winter? Feeding a snake in its primary enclosure can make it aggressive. I break a lot of the rules and feed all of mine in their enclosure. My experience is that those that bite and are naturally aggressive stay the same as do tame snakes (meaning that they stay tame). All of my snakes have triggers that make them aggressive. For example, my false water cobra will try to bite anytime you take her outside in the grass. I have a children's python that is food aggressive. I used to have a large female Colombian boa that would also hiss outside or if food was present. Could be a breed thing. I would not worry. Unless something has changed, they will probably return to normal soon enough.