What would happen if fish took over the world?

If fish took over the world, we might see a dramatic shift in ecosystems, with aquatic species dominating land and water environments. Humans could face challenges adapting to an aquatic-dominated planet, potentially leading to the development of underwater cities and new technologies for survival. Social structures might change as fish species establish hierarchies based on size, intelligence, or adaptability, creating a unique aquatic civilization. Overall, the balance of life on Earth would be profoundly altered, leading to unforeseen consequences for all species.