Swim like a dolphin

Conquer the water! To swim like a fish is a misnormer, as humans we can never swim like a fish's side to side movement. Our vertebra doesnt move this way.
Do you know why the butterfly was developed? It was evolved from breastroke as a way to swim faster, mimicking the dolphin's bobbing motion. Its the 2nd fastest competitive stroke after freestyle.
So the correct phrase should be "swim like a dolphin".