Wow....sooooo I'm going to push back on a loooooooot of the stuff here because I've done it. Here's how:
Buy a group of 6 damsels. They'll spend some time establishing a pecking order, and then a pair will form. I did it in a 29 gallon tank. The important part is to get a group of 6 or more, so that any aggression is evened out within the group. This also conveniently gives you a 99% chance of having at least one male and one female within the group fish can't change sex. You will see aggression, but this is normal. If any one of the fish starts to look super torn and tattered, then remove it from the tank (give it back to the fish store, nurse it back to health, whatever). If you see a pair of fish consistently swimming near each other/nesting together, then you have your pair.
A lot of people seem to forget about this method in the hobby, even though it's one of the oldest ones out there. People see "oh, they're all going to change sexes! I'll only buy 2!" while failing to take into account intraspecies aggression, and other factors necessary for determining if a fish is going to change sex or not. Yeah, saltwater fish are expensive, but this method works. I've used it on firefish and yellowtail demoiselles, and have plans to use it on randall's gobies next. Bidirectional hermaphroditism does exist, but if they're protandrous/protogynous, once they're reached their final sex, that's it; no more sex changes. And we don't know nearly enough about some fish to know "oh, they're juveniles at this stage, females at that stage, and males at that stage" especially when there's no sexual dimorphism at all.
Unlike species like clownfish, wrasse and angelfish, damsels are born either male or female and do not change sex so unless you happen to get a male and female you will not get a pair.
No. Clownfish are damselfish...we forget this too...
Chrysiptera in particular are known to be a protogynous (i.e. juvenile->female->male) hermaphrodites.
