Fighting kittens?

Question
I adopted them a couple weeks ago. The female came home the day both adoptions were finalized and I brought home the male yesterday, he wasn't ready to come home at the time. They're both fixed (he was fixed yesterday) but they keep fighting each other. Yesterday the female was doing a lot of hissing at him and trying to attack him so we kept them in separate rooms. Now they're just fighting all the time. He doesn't hiss at her at all. She still hisses at him here and there. Not as much as yesterday where she would hiss every time she saw him.  We only have one big litter box so we can't really separate them. I just don't know what to do. I'm afraid they're going to open up his stitches if they keep up this rough housing. They don't seem to be hurting each other but they're definitely making me nervous.

Answer
Marcia,

First of all, congratulations on adopting the two kittens.

Cats know each other by scent. A visit to the vet's office, especially having surgery, temporarily gives the male (in this case) a different scent, so the female does not believe she knows him. When cast do not know each other, they need to go through a lengthy (in our terms) "getting to know you" ritual usually consisting of hissing, spitting, fighting etc. If the neutering were done correctly, he should not have any stitches, so this may not be an issue (but you can check with the vet).

When cats "fight" they make it sound like World War III and may even loosen up some fur, but, generally, no one gets hurt!!!!!!!

If they had been friends in the past, this should subside once the boy's scent gets back to normal.  So, in my opinion, the best thing to do is to keep an eye on them, but them work it out. At this point separating them or intervening in any other way will be counter productive. My bet is that within a week or so, they should be OK together as they were before.

Often cats do this "fighting" as a way of showing affection. Cats have incredibly tough skin, so biting & scratching behaviors are a normal way of playing and showing affection amongst siblings.

In any case, what you may have to do is to socialize them to humans if they carry out this biting & scratching behavior with you as we humans have relatively soft skin.

Please let me know how they adjust to one another.

Best regards... Norm.