Tom Fixed and still fighting..why????

I got Felix fixed because of his ball getting injured and hanging out...I also wanted to keep him from roaming. He has never been a fighter and has always run as fast as he could away from it. Oddly though he is still being attacked by my neighbors Tomcat...( I had to chase it off today)...If he is fixed why is this still happening? Also when he saw some of my new kittens...why did he start to hiss and growl at them and their mother through their cage when he has never growled or hissed his whole life(Ive NEVER heard him except when the neighbors dog had him up the tree once)??

Maybe try keeping him indoors for a while, in an isolated room...I am not an expert on this type of behaviour, but if I were you, I would maybe give the vet a call and ask advice from him/her...GL!

I'm not an expert on this either, but it's possible some male hormones are still in your cat's system. Some toms will attack and kill newborn kittens so that their mother will go back into heat. Maybe your cat was hissing and growling at your kittens for the same reason. I agree that it would be a good idea for you to discuss your concerns with your vet.

There are still hormones in his system, he needs to stay inside as much as possible. If it was the neighbors tom that injured him he will still see him as a threat. You may not have heard him growl or hiss as he has mostly been outside and may not have behaved this way in your presence. Give him time and he will calm down.

I agree with keeping him indoors for awhile, plus he is stressed from his recent fight, and his trip to the vet and subsequent surgery. He needs to decompress.

seems the majority of everyone says it's hormones...that's about all that would make sense (he's always been too scared to fight and runs/hides from attacker even when he could win)..If he is inside or outside, how much longer untill his hormones are calmed? Even if they are calm will he always be a kitten threat? Thanks.