As many here know, I am not a believer in "experience" trumping scientific fact. We learn what a species requires in an aquarium by studying the habitat, and many sources, sites like Seriously Fish, CorydorasWorld, Planet Catfish, etc, have done just that, or used the knowledge of those biologists who have. If I were to ignore this and keep "x" with "y" it is likely I would not have a clue as to reading the fish's signals, unless the extreme presented itself (physical aggression leading to death). And such "experimentation" is inhumane because the fish is forced into a situation it does not understand and is more likely to suffer the consequences.
Angelfish do not occur in habitats that have fish charging around them; at least, I have never seen video evidence or verbal suggestions of this. The angelfish prefer to remain among branches, sunken logs, tree trunks and roots, or in some areas plants. The water is dimly lit due to floating plants or more often the forest canopy. From my published profile of Pterophylum scalare:
Origin and Habitat: Occurs in several rivers in the Amazon basin including the Amazon itself (Brazil, Peru, and Columbia) and in the Rio Oyapock (French Guyana) and Rio Essequibo (Guyana). It is found in swamps and flooded forest where vegetation is thick, and in slow-flowing streams where they remain close to the banks around aquatic plants, roots, branches and/or overhanging vegetation.
This is one reason they are so well suited to have tankmates like discus and black ghost knife fish--though I am not recommending discus, these should never be combined with the more aggressive-feeding angelfish--but the point is that these fish are all sedate and "quiet."
