Question

what kind of adaptation in fish helps in swimming

Answer 1

Unidirectional respiration in fish is the one which takes water through the mouth and releases by gills - but man takes in and expels air by spending energy and it is not unidirectional.

This saves energy and helps forward movement.

Scientifically, fish are capable of propulsion by making use of especially the caudal fin or tail.

Fishes can rise upwards by generating hydrodynamic lift with the pectoral fins and caudal fin and making use of swim bladder.