snailhave,
The tail wiggling is a sign of aggression. In a way they're trying to fight on who's the more dominant. They're supposed to do this, but please watch them, things can get really ugly. When you said kissing the cheek spine, that might just be the smaller one trying to nip the bigger one.
If things do get ugly, what I learned to be the best way to catch fish, esp clownfish, is at night. Let the lights out at night, and they'll go to sleep. When they're at this stage they're unaware of their surroundings. So it's easier to catch them.
Try that. I hope this helps.
stupid_naso