The royal angelfish or regal angelfish, Pygoplites diacanthus, is a species of marine angelfish of the family Pomacanthidae, and the monotypic genus Pygoplites. It is found in tropical Indo-Pacific oceans. Its can grow as long as 25 cm.
In the aquarium 
Although it is frequently exported through the aquarium trade it rarely survives in the aquarium.
Usually specimens abused during shipment, more likely caught by drugging, will refuse to eat anything, including live fare.
However, given the right environment, specifically with smaller and docile tankmates like gobies and dwarf angels, it will start feeding within days when fed brine shrimp, brine shrimp plus flakes, and further progressing to regular frozen foods and a certain brand of cichlid pellets which this species seem to crave.
With a hostile environment with fellow large angels, puffers, and triggers, and certain clowns, it will almost certainly fail to acclimate and slowly die of starvation due to its shyness to start feeding.
Survivability of feeding specimens seem to equal to the other Pomacanthids.
Fresh water dips may be required to rid newly arrived specimens of flukes and ick which this species is especially prone to.
The prior myth that only yellow-bellied variations from Sri Lanka and the Red Sea will survive points to the fact that specimens from the Philippines and Indonesia are often abused when collected.
See also 
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