Definition: To move in water by movements of the body or parts of the body, especially the arms and legs.
In the case of fish or any animal with a tail and fins, this ASL sign doesn't apply. Use the classifier for fish swimming instead.
Gloss: /\RIVER/\ /\MY BROTHER/\ IX1 CAN SWIM CL:bank(passive hand) CL:1-across-river(pathline+aah).
English equivalent: My brother can swim across the river.
Assertion (nodding) for CAN; mouthing "aah" for the pathline which indicates a long (or slow thus long) swim. The pathline has a shaking movement which indicates a long or slow and long path.