[ray-the-pilot]

One of my favorite tanks was a 29 gal with Angels, neon Tetras, Cory Cats, et al. I started with six Black Angels and when they paired of and began to spawn I gave away the other four. The tank was great for some time with the neons shoaling on the side of the aquarium away from the Angel nesting site.
When I first purchased the Neon’s they were small enough to be dinner for the Angels but the tank had plenty of hiding places for the smaller fish.

 

[ray-the-pilot]

The problem is that you cannot determine the sexes of young Angels. And even if you could they may not pair off.
If you can afford it, then buy a pair that has already mated and you can get away with just two. You might have trouble finding such a pair as people don’t generally part with them.