fish
A piece of wood or metal secured to the side of a beam or the like to strengthen it; particularly, when used to secure two timbers or the like, when joined end to end. In the latter case, two fishes are generally used on opposite sides; sometimes four. Also called fish piece and fish plate. (Sturgis, 1900) 2. A symbol of Jesus Christ, particularly used by early Christians. (Kremer, 2025)
Photo from the Detroit Institute of Arts, Detroit, Michigan, 2025.
fish piece, fish plate