Any clues on what I should look for?
Are 2 fish "pairing up" and chasing the others away?
Sometimes the pair will lip-lock and wrestle.
Brighter colors, esp. metallic blue/green spots here and there (on fins on my fish). Extra big belly.
Biggest clue, look at their anal vent. Anything protruding? Female will have a fatter egg laying tube like organ, males is a skinnier organ. Cant remember names of organs, but you get the picture!
How many angels do you have again? I have three, they did not pick on the odd man out too much, but sometimes when forming a pair, the "winning" male will beat the other male(s) badly, even killing them. Mine just had a few fin tatters, so i left them all together. Be careful, you may need to separate somebody out.
Still no succesful hatching in my tank, someone keeps eating the eggs during the night time.
Also, any extra large water changes lately? I just learned this, Angels can be somewhat induced to spawn by a large water change, it simulates the rainy season in South America. Live foods help too.