My guess is that the fish are photoshopped there, considering the size of the tangs, lack of filter, and heater(don't know what that oval device is, but it's not in the water)
Although it is a bad example of animal husbandry, no one who does 3 minutes of research on reef keeping will think that is ok. and if people don't do 3 minutes of research, chances are, the fish dies anyway.