Why do fish lives in water?

Fish live in water because they are adapted to do so. Their bodies are streamlined to reduce drag in water, and they have gills to extract oxygen from the water. They also have fins to help them swim.

Fish cannot survive out of water because they cannot breathe air. Their gills are not able to extract oxygen from air, and they will suffocate. Additionally, fish need to be in water to maintain their body temperature. When a fish is out of water, its body temperature will quickly drop, and it will die.