Shoal of Pomacentrus alleni

Was thinking about just having a shoal of these and nothing else in my tank fishwise my tank is 24" x 16" x 12" and around 15g. Just wanted to know if these do better in shoals of odd or even numbers? Also how many for my size tank?

 

Damsels can be pretty territorial and IMO 2 would be pushing it in a 15 gallon. Even with that its still Iffy, says here (Saltwater Aquarium Fish for Marine Aquariums: Neon Damselfish) they need at least 30 gallons.

 

I think 2 would probably kill each other in a 15g... Fish don't really shoal in our aquariums anyways. In nature, they generally shoal to feed, defend against predators or defend a food source. In a 15g, there is no reason to shoal to feed, no large patches of food to defend and no big predators, so instead they will probably just fight...

 

I've read these are the "least aggressive" out of the damsels, but granted they're still a damsel.

Back to the drawing board perhaps?