Three Stripe Damselfish

I have 6 of these in the tank at the moment.  They spent most of their time hiding in the rock for the first month.  Lately, they've been out and about more.

Scientific Name : Dascyllus aruanus
Common Names : Banded Humbug, Zebra Humbug, Domino Damselfish, White Tailed Damselfish
Damselfish Care Level : Easy, good for saltwater aquarium beginners, but don't use them to cycle your tank! Using live rock is currently one of the best ways to cycle a tank fishless.
Life span : 3 - 5 years, possibly longer
Size : Around 4 inches (10 cm)
pH : 8.1 - 8.4
Temperature : 75°F - 80°F (24°C - 27°C)
Specific Gravity : 1.020 - 1.025
Carbonate Hardness (dKH) : 8 - 12°
Origin / Habitat : From the Indo West Pacific and to South Japan.
Temperament / Behavior : Much like other damsels, this one can be aggressive and even more so as it matures. They may not tolerate other damselfish in the same tank and less aggressive tank mates may get bullied.
Breeding / Mating / Reproduction : Males form nests in the substrate and entice females to breed. Afterwards the males guard the eggs until they hatch and enter the water column.
Tank Size : 30 gallon minimum
Compatible Tank Mates : Avoid keeping them in an aquarium with Lionfish, Snappers, Groupers, Triggers, Eels or any other predatory fish large enough to eat them.
Reef Tank Compatible? : They shouldn't bother the corals, anemones and other invertebrates. Some have reported that they will nip at hermit crabs and shrimp species.
Fish Disease : Saltwater Fish Disease - Diagnose, Symptoms and Treatment - This is a fairly hardy species like many of the other damsels. Using damselfish to cycle a tank used to be one of the advised ways of cycling marine tanks.
Diet / Fish Food : Omnivore - they will do best with a variety of foods. Small marine origin meaty foods along with some herbivore rations will be good for them. Frequent small feedings everyday are advised.
Tank Region : Middle to bottom and usually near cover of some sort.
Gender : Difficult to determine from external features.