Whales are not fish, but mammals, and they are viviparous (whales are also the largest animals in the world, but not the largest fish, and the largest fish is whale sharks)

Turtles are not fish, but reptiles/amphibians. You can tell from the surface, but their hands and feet have been soaked in water for a long time and evolved into fish-like fins. However, turtles are oviparous, but their breeding ground is sandy land. Larvae need 80-90 days to hatch before entering the sea.

Fish are originally oviparous and are characterized by breathing through gills. Secondly, unlike whales/turtles, fish have scales and fins.