These are the fish I am currently housing in a 16 gallon tank:
- 3 Scalare Angelfish
- 6 Zebra Danios
- 1 small Common Pleco
- 3 Boeseman Rainbowfish
- 2 Ramirezis
This was the largest replacement tank i could find for them when my 50 gallon suddenly sprung a leak.
I haven't seen any signs of aggression, but I'm sure there will be problems between the Angelfish in the long run. Of course, I'm relocating the fish to my 50 gallon once the silicon sets well enough.
I'd say frequent water changes are a must.
Also, try to include a few live plants, as these will help with oxygenation and will actually use up some ammonia, nitrites and nitrates in the tank. The plants will also provide some cover in your tank, which should aid in reducing aggression.
Be aware though, that Angelfish can get pretty big, and that you may need to find them a new home when they grow up.