How do fish swim?
Most swimming in fish is the result of the muscles on the sides of their bodies. You might not ever have thought about how you walk or run, but what you are doing is pushing off the ground with your foot to move you forward. Fish use the muscles on the sides of their bodies to push against the water in a similar manner to swim. -muscular tails for direction and push -swim bladder for buoyancy [helps them adjust whether they sink, float to thetop, or keep going straight]
When the muscles on the right side of the fish contract, the tail is pulled to that side of the body, which pushes water backwards, propelling the fish forward through the water. Then the muscles on the right side relax, and the left side contracts, pulling the tail the other way, and this cycle is repeated over and over to produce thrust.