If you want to keep him from becoming aggressive, make sure to be very, very calm around him.
Roostersandhens,
It's fairly invasive, but, in the end, all of the chickens will be happier.
I have caponized >30 boys, and lost three, from bleeding. It's not difficult to do, but, it is tricky, to avoid nicking the artery that the testes are attached to. Every one of those who didn't die from bleeding, were up and about, minutes after the surgery, and their incisions were healed closed, within 3 days. There is some pain involved. But, it's not as bad, as one might imagine.
I understand that you are an animal lover, and possibly an activist. That's good. We need some of y'all, in society, it keeps things straight, and people honest. But, there are times, where doing something invasive, will make life better, for all involved. They get over it, faster than you'd imagine.
Chickenlove63,
I would recommend the procedure, if you can find someone to do it. Check all of your local feed stores and farmer's co-ops, and ask if they know anyone who caponizes. Also, look for local Facebook groups, dedicated to farming, and check for a group local to you, here on BYC. Likely, there is a W.VA. thread in the where are you? Where am I? Forum. Someone must know how to do it.
I already have several folks lined up, who want me to do their boys, here in E. OK, and NW ARK., come springtime.
But, understand, it's not like surgery on a human. To do it in the same sterile and professional setting as surgery, makes it cost prohibitive, and it becomes impossible for most. With about a 10% death rate, it's quite likely, that your young roo, might not make it. You might want to consider taking him to a swap, or advertising him, to trade, for another hen. Once caponized, ALL of their "rooster instincts" are gone. No fighting, but also they stop feeling compelled to be defensive of anyone, other than them selves. All of my Capons get along well with my roos, and hens. They might get into a spat, over some morsel of food or such, but there's no fighting for dominance, and no sexual interaction, between them and the hens. So, they will not defend the girls, against any predators.
You likely need to examine if you really want a rooster, and if so, why. My roos are all purebreds, and I plan to eventually breed them, so I keep them sequestered, with their girls (of same breed) from the other roos. My biggest, most protective roo, gets the main flock, to watch over, as he is a gentleman, to the ladies, and with 40+ hens and pullets, he's not overly affectionate to any of them, in particular, so they get to spread around the "wifely duties", and none gets too much attention.
If you're squeamish about consuming fertilized eggs, I'll add this. I was a city-slicker, up to a year ago. Moved to the country. Got some birds. Been absorbing info, like a sponge, to water. I, too, was a bit squeamish. I now know how to tell a fertilized egg, from one that isn't. I just don't care, anymore. There is ZERO difference in flavor, and the difference in appearance, is only apparent to those who know what they're looking for. So, if you're just squeamish, about that, you'll get over it.
I am in the camp, that likes having a roo around. A good roo, will share food with his girls, protect them with his life, and help gather them, when it's time to get in the coop. Consuming fertile eggs, is no big deal, compared to that help, with the flock. But, if you don't have plans for getting more hens, you might be better served by a capon of no roo at all.