Dragon Ball Episode 005 - Yamcha the Desert Bandit (English Dubbed)

Bulma, Goku, and Oolong are in a boat passing through a river. Bulma decides that Oolong and his shapeshifting ability can be very useful in their quest. Oolong then changes into a fish and jumps out of the boat when he hears that the next place they are going to is Fire Mountain.