Help! My male cats won't stop fighting!!

Ok so here's our problem. My husband and I have 3 cats, 2 are male and one is female, Kleo-female, Rex-male, Abby-male. We had Kleo first and we adopted rex and abby, they are brothers and we've had them since they were kittens. For about the first 8 or 9 months we had the abby and rex in the upstairs of our home and kleo downstairs because Kleo was still being somewhat hostile and considering she is 25 lbs and they are about 10 lbs each we wanted to be very careful. Now here if where my problem starts, we finally got Kleo used to the other 2 and she doesn't really care about them or bother them. Rex was much more timid and preferred to stay upstairs most the time while Abby liked to explore downstairs, but when Rex finally got comfortable downstairs Abby started chasing him back upstairs and starting fights with him anytime they were in eyeshot of each other. This has been going on for months now and it's getting worse not better. At night my husband and I have always slept with the 2 brothers in bed with us (Kleo is very independent and likes to sleep alone) and it was never a problem, now they fight all night long. I don't know what to do, we're at the end of our rope, and we're loosing a lot of sleep. I'm sorry this post was so long but if you have any advice please help me! By the way all 3 cats are fixed.

 

usually 2 males will get along quicker than 2 females.
Perhaps it's as simple as them trying to establish dominance over one another "I'm boss" "no I'm boss" "No I am"
there is a product you can buy called Composure Liquid. It's kinda pricey (at least by my standards) but it works pretty well.
My Dixie cat usued to beat my one male cat up all the time. My vet gave me some of that and Dixie hasn't beat on Zeus in quite awhile!! It's not a prescription so you can by it online too.
worth a try for some sleep

 

Good luck with your furbabies!

I can't offer any help as I had the same problem with Rene recently. A few weeks after Pumpkin passed away, Rene became unbearable to the other kitties. They'd be fighting day and night. It got so bad that Milo shredded up Rene on a daily basis and vice versa. We had no choice but to send her to my husband's parents. The boys are happier now at home and have started going into rooms where Rene used to dominate. Actually, she dominated the whole house. Rene is also happier at my in-law's because she is getting 24/7 attention now that they are retired. I just supply the food, litter, toys, etc. She adjusted well in just 2 days. The problem was that Rene enjoyed being the only child. We all miss her terribly including the kids. My 2 year old asks me constantly where's Rene. :cry:

We will take Rene back if there are any problems and will try the Composure Liquid. I wish I had know about it sooner Mary.

 

I may have missed something here...

are these boys neutered? If not, this is the problem. As a former breeder occasionally I neglected having one of the males that I kept neutered in time and he had the misfortune of dealing with his father....not to pleasant.
Even after neutering the fighting went on when ever one of the queens came into season. This lasted for about 6 months until the tom no longer saw his offspring as a threat. If not neutered, a male cat is a tom by nature and will become very territorial.