Comic Strip / Slylock Fox
How does Slylock know the painting is a forgery? Because salmon don't swim downstream.

Slylock Fox and Comics for Kids is a newspaper comic strip by Bob Weber Jr., which consists of the Slylock puzzler and a number of other activities. The puzzler consists of the professional detective Slylock Fox and his assistant, Max Mouse, solving a number of mysteries, usually stopping a number of recurring villains.