Fish holding apparatuses and methods of using the same are disclosed. Embodiments of a fish holding apparatus include: a first plate; a second plate coupled to the first plate, the second plate rotatable relative to the first plate about a horizontal rotation axis proximate and substantially parallel to a bottom edge of the first plate; a biasing member configured to bias the fish holding apparatus toward a closed position; and a holding mechanism configured to maintain the fish holding apparatus in an open position. Other embodiments of a fish holding apparatus (a "caliper") configured to hold open the mouth of a fish include an elongated wire including: two ends having prongs; two arms; and a spring loop configured to provide a spring force.