What is the difference between cetaceans and fish?

Answer 1

Cetaceans are ocean-going mammals, namely the dolphins, porpoises and whales. They have hair (yes, they do, go ahead and look it up, whale facts are pretty interesting:-D ), they give live birth and feed their babies on milk produced in their mammary glands, they breath air through lungs and are warm-blooded. Fish are cold blooded, breath through filtering oxygen out of the water through their gills, have scales on their skin, lay eggs and do not nurse their young. Physically, you can tell the difference right off, even from far away - their tails! Fish wear their tails up and down, and swim with a side-to-side motion, while dolphins, porpoises and whales wear their tails flat, and swim with an up-and-down motion. :-D

Answer 2

Cetaceans are aquatic mammals that breathe air, give birth to live young, and nurse their offspring with milk, while fish are cold-blooded aquatic animals that typically breathe through gills, lay eggs, and do not nurse their young. Additionally, cetaceans have a streamlined body with a horizontal tail fin, whereas fish have a more diverse body structure with vertical tail fins.