Intelligence, coordination and slipperiness. Also, to rephrase your question correctly, "How do fish in schools swim without colliding with one another."
The ray-finned fishes are characterized by having fins supported by bony spines or rays. They also have a skeleton made of bone, scales covering their bodies, and a swim bladder for buoyancy control. Ray-finned fishes are the most diverse group of fishes, with over 30,000 species.
to swim
Thats how they swim
they swim
Yes, all whales are fishes because they swim like fishes.
separate vertebrate
Yes they can swim.
salmon
they swim not run
Yes. Fins, a swim bladder, the composition of their bones, and their muscles all help a fish to swim.
Nope. Piranhas are freshwater fishes.
they die