A shellfish trap has an entrance throat (3) and an annular plastics insert (5) releasably engaged in the throat and provided with two flaps (7) in the form of branched stems extending across the ring (6) constituting the body of the insert at its end furthest within the pot. The flaps (7) each have a releasable hinge connection (30, 32) to the ring (6) and can be pushed open to let a fish into the pot but are biased by a leaf spring (38) to close behind it to prevent its leaving, the free ends of the flap branches abutting end surfaces (l3, l4) of the insert to prevent pivoting beyond the closed position.