The Story of Lemuria would be so attractive to fishman. And Miryam and Goliath would absolutely know it.
Imagine. Your people are calling "Fish"man. Then someone come and say, no Our people have a True name. Fishman is a degenerate name. To make us lesser then them. We are the descendents of a great kingdom. A Kingdom that survives the great flood by the blessings of the god, who gave us gill to breath. Hands to control the sea. And voice to command the sea creature.
People would drink those up.
It'd serve as a legitimate threat to King Neptune's rule as well, mostly due to how stuck in mourning the entire royal family is after Otohime dies AND how they can't seem to handle Vander Decken. Makes them seem incompetent, especially if the Seafarers are providing 'miracles.'
Like the Seafarers don't have to go "step on Queen Otohime's picture, reject everything she did" like the New Fishmen Pirates did for legitimacy because their purpose is not in direct opposition.
They can just skirt around that by saying "Queen Otohime meant well, but she was misguided." AND still appeal to Fishmen supremacists among the Fishmen Pirates, new and old, because they're still saying Fishmen are better than humans.










