Biting is part of the natural behavior of ferrets. They may bite to get attention or as part of play. Sometimes ferrets nip out of fear. This is often seen in young male ferrets 3 to 4 months of age that have spent most of their lives in a pet store with other ferrets but little human interaction.
Like all carnivores, ferrets have large canine teeth that can be rather intimidating because they usually hang lower than the lip flap and are in view. Make no doubt about it, though, the bite of a disgruntled ferret is painful and can draw blood.
Biting is not cute and should not be encouraged through play. It can get out of hand and may become a behavioral issue. If your ferret nips, immediately tell him "No!" and place him in his cage. In this way, he'll begin to associate biting with jail time.
If you have a kit who continues to nip and bite despite frequent scolding and spanking, you may wish to discourage his biting with Bitter Apple. It comes in a spray bottle and has a taste which most animals find very unpleasant. Some ferret owners say that they've found it very effective if sprayed in the animal's mouth and face when he is in the middle of a nip, and they report that after using it for a few days to a few weeks, their pet learned not to be so rough in playing with them and the nipping habit ceased.
Ill-tempered ferrets should not be bred. Biting and nasty temperament seem to be dominant rather than recessive traits, and if you cross a biter with a docile ferret, it is quite possible that to get an entire litter of babies who bite.
Most baby ferrets will outgrow the nipping stage just like kittens or puppies. But until they do, do not point your finger at one. A ferret may think you are either an enemy or food, and either way, you probably will get to feel those little teeth. A ferret's nipping behavior is the same as a cat or dog, some do and some don't.
If your ferret nips and hangs on, simply grasp it by the scruff of the neck, remove it, then say, "NO!" loudly (this works for many owners). You may have to repeat this several times until the ferret learns who is the boss. It is up to you to teach him acceptable behavior. Never hit a ferret for nipping. It will only make the ferret nervous and it may then bite out of fear. Another excellent aid for nipping is using a product such as Bitter Apple (or Orange, etc.) to train a ferret to not bite. It can be sprayed on your hands prior to handling. It can be put on socks and shoes for those "ankle nippers." It also can be sprayed along the neck and back of ferrets to prevent fighting. Be careful not spray into ferret's eyes.