You should have an 75G tank at minimum for Discus and Altum Angels get very large, like an adults hand if spread wide open.
Poor OR less than ideal water quality can also cause fish to get agitated.
Temp needs to be good for the Discus like 82F / 27.5C MINIMUM.
FW & SW
Favorite tank right now - 72G Bowfront Wadai Tetra, Cardinal Tetras, Ghost Glass Cat Kryptopterus bicirrhis and Clown Loach Cory haven
New to FW fish? First tank in a long time or EVER??? Need some info on keeping fish?
Start here - Aquarium Advice Article