HI everyone, this is my first post. I'm wondering if anyone could take a guess at my angelfish ages. I have eight in a 35 grow out tank with plans to separate as they pair off. I've had these for over a month now, I bought them off a hobbiest. The marbles are about quarter sized and the zebras are about half dollar size. How will I tell they are pairing off and when should I start to notice that? Thanks in advance!