swim bladder
it help the fish to move swiftly threw the water
my dicktionary
They both help a fish to move
to move up and down in water
to move up and down in water
With their tails; although the subs is mechanical.
pushs the fish to move
Fish have fins instead of legs. Fins help fish navigate and move through water by providing stability and propulsion.
Fish move by swimming. They move their fins back and forth to swim. Some fishes have a swim bladder which is an organ that help bony fish stay in different depth.
A guppy is a fish and it swims in water. , Generally, they move up and down, side to side, and their movements are sometimes based on gender.
Because if fish had fur then the fur would get wet and weigh them down and they wouldn't be able to swim very well. Scales help them move swiftly in the water and give them an armor-like outer covering.
Dolphins move up and down. Fish move mostly in a straight line.