I have a nine month old male Vizsla who wants to play bite and can be aggressive at time when he is "playing". I try to discourage all types of aggression behavior and give him a stern NO! when he tries to nip at my fingers. He comes back harder if I try to correct him by putting him in a down or sit position.
When he was 12 weeks of age we attended a group obedience course that also included the "no bite" correction method. Basically you grab them by the mouth and curve their gum around their teeth as you give him a stern no. He is supposed to lick and then you quickly follow that with praise. I have learned that this method does not work or makes him even more excited.
I run him and take great deal of time with walks and reinforce training such as heel, stay, wait, etc. I don't know why he gets in his head that it is OK to bite and completely ignores me when I try to correct him. HELP!