They do need very clean water, so a good filter is a necessity. Like most cichlids, angelfish are voracious carnivores. They will gobble up brine shrimp, mosquito larvae, drosophila and even worms. Commercial flakes can be used, particularly if specially formulated for cichlids and angels, however, live or once-living foods should be offered regularly for best results. Of course, angels are notorious for eating smaller aquarium fish.
Angels are seemingly among the most alert and intelligent of aquarium fish.
They can learn to recognize their keeper and will even accept morsels direct from fingers. They also have several other interesting characterstics. Some have been known to become so bonded to a partner that if it dies, the survivor will stop eating and perish as well, presumably from sadness. In such a situation, a change of water conditions might snap them out of it, or perhaps an alteration in diet could work. Squabbles and scuffling are not unusual among angelfish, even a bonded pair.