8" tilapia in a 29G tank is really crowding it.
The "king" is the alpha male, and I bet if your tank has sand substrate you would find it would build a nest. The rest of the tilapia are lesser males and females. The best way to find the females is to wait for them to lay eggs and mouthbreed them.
Also, make sure there are some hiding areas for the lesser tilapia to hide from until you can get a bigger tank.
It sounds like you got regular mixed sex tilapia.
Forgot to mention a number of things:
1) I have noticed that the alpha male only "acts up" when a/the female/s become mature. So there must still be at least 1 female in the group.
2) too few females (when they cant hide) often results in "battered wives", eventually dead ones if the situation is not corrected soon enough.
Totally agree with both of those Joel.