I believe you tank is too small for your angel. Read below, also added a flame angel description. I believe 30 gallons to be too small for a flame even though that website says they can go into a 30.
French Angelfish
(Pomacanthus paru)
French Angelfish
Quick Stats
Minimum Tank Size: 100 gallons
Care Level: Moderate
Tank Conditions: 72-78°F; sg 1.020-1.025; pH 8.1-8.4; dKH 8-12
Max. Size In Aquarium: Up to 1' 3"
Color Form: Blue, Yellow, White
Temperament: Semi-aggressive
Reef Compatible: No
Diet: Omnivore
Origin: Caribbean
Family: Pomacanthidae
Flame Angelfish
(Centropyge loriculus)
Flame Angelfish
Quick Stats
Minimum Tank Size: 30 gallons
Care Level: Moderate
Tank Conditions: 72-78°F; sg 1.020-1.025; pH 8.1-8.4; dKH 8-12
Max. Size In Aquarium: Up to 4"
Color Form: Orange, Yellow
Temperament: Semi-aggressive
Reef Compatible: With Caution
Diet: Omnivore
Origin: Christmas Island, Cook Islands, Marshall Islands, Tahiti
Family: Pomacanthidae