Here’s some of my experiences how to keep angel fish in a reef tank
1) try to get juvenile fish. They haven’t got a taste for coral yet so less chance of nipping.
2) Feeding schedule through out the day. Best way is with auto feeder because u can feed small quantity. Nori clip for them to gaze algae instead of corals.
3) corals selection is the key. Sps , Torches , Hammer, Frog spawn , Elegant , Mushrooms, Soft corals , Anemones, Chalice, Montipora so far are safe in my tank. Any meaty corals such as Acan , Donut, Brain , Scoly are at risk. Clam is 50/50 if u have a few angels but for my tank is dangerous.
4) Angel fish selections. Reef safe angel is a no brainer Lamark, Japanese swallow tail , Flame . Angel with big mouth have less chance of nipping polyps because they rather eat larger food items like sponges. However with angel fish its a hit and miss so u have to decide is the fish is more or less important compared to your corals.
A tank full of variety of angel fish is awesome. They dont get super aggressive like tang and their color is spectacular.
Hopefully this will help for anyone who wants to add angel fish into their reef tank however its still a risk of bad behavior fish.