Whoosh.....I've caught and cleaned a lot of fish in my time. And frequently sorted through the innards to see what they were eating. But I NEVER saw any balls. Unless we're talking "Milt Sacs" that is?
Fish balls are simply various processed fish "parts" mixed with a binder into a type of "fish paste". The Asian version of a hot dog and comes in all sizes, shapes, colors and various seasonings. Dense cake form, "balls", fried, ... you name it... but essentially all the same difference.