text: why do u think about this? why don't fish fly and birds swim? tricky question!! well, there are fish that can "fly": certain species can jump out of water up to 3-4 metres in height. not to mention the dolphin, when it jumps it goes up to 10 m without touching the water, so it's flying. there are also birds that swim: ducks. also deserve to be mentioned the species that dive to catch fish. ha ha got u there