First, congrats on your new Angelfish!
The 'kissing' can be one of two things, but both being aggressive behavior.The reasons for the behavior may be different tho. One can be that they are both males and are fighting, (lip locking) in a battle for dominance. OR they are male and female lip locking as the female wants to see if the male is a strong one and worthy of pairing with.
Since it is just these two that are doing that, and the lip locking is not extended to the other Angel fish, it may very well be a pairing off ritual.But then again, its very hard to be able to say for sure at this point.
How old are the Angels in question? Do you have any photos that may help us to determine the gender for you?
