Abstract: A fish measuring device preferably substantially contains or surrounds a fish, and thus calms the fish, and provides a relatively quick measurement of the fish's length. An elongate tube preferably contains a capped end with a visual inspection portion proximate the capped end. A cut out distal from the capped end preferably includes a primary length indicator. When a fish is measured, the user places the fish in the tube, preferably under water, with the tube partially filled with water, or with the tube previously wetted. The user visually confirms the nose of the fish touches the capped end and reaches through the cut out distal from the capped end to squeeze the tail fins of the fish together. The user compares the position of the squeezed tail fins against the primary length indicator, preferably to determine whether the fish is shorter than, or at least meets, a legal length limit.