Most fish use their side,back,and tail fins for swimming.Fins are movable,fanlike parts.A fish moves through the water by swinging its tail fins back and forth.A fish uses its other fins to steer and to stop.Sometimes the other fins also help it go fast through the water.
Most fishes have bodies shaped like a torpedo.Their bodies are pointed at the head and at the tail.This streamlined body helps fish speed through water.Sailfish can swim as fast as 70miles per hour (110kilometers per hour).
Some fish have unusual shapes.Rays have flat,disc shaped bodies.Large fins like wings go out from a ray’s head.To swim,rays flap the fins.
Most fish also have swim bladders.They fill their swim bladders with air.Their air filled swim bladders act like life jackets.They keep the fish from sinking to the bottom.
How Fish Breathe