Thelma

Thelma is a plastic singing fish that Mr. Sipple gives Arthur and D.W. in the episode "Arthur and Los Vecinos," when he moves away. Though Mr. Sipple gave her to both of them, D.W. has since taken the fish for herself and made it her pet. Since this episode, Thelma has made frequent appearances.

Thelma is a fish on a plaque-type board. When you press the button on the board, the fish's front half turns toward the person who pressed the button and sings "Row, Row, Row Your Boat."