I currently have Ryunkins, Orandas, PearlScales, and LionHead. LionHead and PearScale are slower than oranda and ryukin. However, I don't have any problem during the feeding time because I have used the "Feeding Dish" method from Obsidian on "Tip of The Month" to feed all my fishes.
You can find this method at the link below.
http://www.kokosgoldfish.invisionzone.com/...?showtopic=8779I currently have three dishes on the bottom of the tank.
I always feed the fastest fishes first. When their mouths are full of food, they don't bother the slower ones' dishes.
This way, all slower fishes get enough to eat.
I don't have any blackmoor in my tank so that I don't know you can mix with oranda and ryukin or not. I heard that blackmoors are very slow. However, you can train your blackmoors to eat on the separate dish.
My fishes do not fight. They are very peaceful.