Blood tide

the long version

Megalops is an Aquarian, a human-dolphin hybrid who lives in one of the many reef-cities that thrive beneath the waves on an Earth ravaged by climate change. Some of the Humans who cling to the barren lands blame Aquarius for their plight and unleashed the Medusa Plague that entombed Megalops's wife and daughter in stone. Tormented by that loss, Megalops dedicates everything to avenging his murdered family, no matter what the cost. He unleashes a Vendetta Virus as cruel and lethal as the Medusa Plague, a bio-weapon that transforms living Humans into Aquarian corpses.