but you're right, the butterflyfish family (Chaetodontidae) is marine. They are shaped like discus, only much flatter when viewed from head-on. That's why scientific names are used, because common names don't really mean anything and change by time, region, even coloration of the fish.
Another example, spiny eels and peacock eels aren't true eels at all.
Another example, spiny eels and peacock eels aren't true eels at all.
