Your last two posts were after 12 am and 2 am... generally, you're not going to get a flood of responses by 7 this morning... patience. Also, you're not asking specifically about all male tanks in your other posts.
Stocking an all male tank is really more about two things: The size of the fish and their appearance. For a four foot tank, stay away from fish that grow beyond seven inches or so and always avoid two of the same species and two fish that closely resemble one another. From there, it's pretty much up to your own personal preference as to what you stock. Have a read of this article for more info.
Hi Natalie! I also have an all male tank. Here is my mix, which is working extremely well
Copadichromis mloto ivory head
Red Empress (too big for my tank and for yours, but he was misidentified and I don't want to get rid of him yet.)
Plus 3 labs, 1 p. acei and 4 synodontis multipunctatus.
No I have no trouble with aggression in this tank. The only chasing is among the syndontis! The Red Shoulder doesn't have much red on him, so he really doesn't look at all like the ruby red. I was thinking the Eureka Red might be an issue, but he isn't either. And my red empress is the "big guy" in the tank and never harasses anyone. Of course, I did seriously threaten to take him back to the LFS because for the first week or so he was chasing everyone. After threatening him (I'm actually not kidding) he settled down!
Actually, I tried to catch him to take him back to the LFS -- and he knew we were aiming for him. And when I couldn't catch him (how could a fish that big hide so well??) I asked a friend who "communicates" with animals to talk to him. Yes, I know, very weird. But I was desperate. She was a bit skeptical and said she'd never talked to a fish before. Anyway, she did her best and I swear, he calmed down after that and was never a problem again. (I also moved some rocks around when chasing him, so maybe that was it!)