Are angelfish clearwater or blackwater fish?

Angelfish have a pretty wide range and are distributed throughout the amazon. In their natural habitat, do they favor clear water (typical of most aquariums) or do they favor blackwater like discus? Blackwater being the tea-colored water after filtering with peat or something similar. I have read information that suggests both although most seem to indicate that angelfish are primarily a clearwater fish. Which is it?

Wetman, thanks for the link.