I came across this excerpt and thought of Lisa's recent angelfish tank. Here is some video of Pterophyllum scalare (the wild angelfish), Paracheirodon axelrodi (cardinal tetra) and Brycons (a larger fish species, something like a trout but not related).
The video says it is the Amazon, but it is not the Amazon River, since P. axelrodi do not occur in the Amazon proper, nor do angels to the best of my recollection. So this is obviously another river in Amazonia. But it is important to notice the darkness in the water that these fish prefer, even though the video is shot during the day as the above-water sequences show. And the fish are all swimming under branches and overhanging vegetation, out of the light. Further evidence of the sort of natural minimal light these fish require to feel "at home" and display their best colouration and behaviours.