All Angels need a MIN 75 gallon+ tank with plenty of rock.  Pygmy Angel fish are constant swimmers & need the space!  Do NOT put them in tanks smaller than a 75g!

You can have multiple Pygmy Angels in the same tank but it's best to introduce them all at the same time.  If that's not possible, introducing different body styles helps potential aggression.  There are 2 main body types in Pygmy Angels:
LB = Long Body (like Lemonpeel Angels, Coral Beauty etc.)

SB = Short Body (like Flame Angels, Multicolor, Potters etc.)

The differences in body lengths makes them "look" different so are assumed less of a threat to each other.

I've found only ONE species of large Angels to be truly reef safe & that is the Majestic/Blue Girdled.  ALL other large Angels should be avoided in a home reef aquarium.