The invention relates to a container assembly comprising a container for depuration of mollusks and a drain canal unit. The assembly provides a closed circulation of water via a circulation route that has an entry portion between the floor of the container and the drain canal unit, a circulation channel between the corner of the container and a drain canal unit, and a drain canal within the drain canal unit. Also provided is a drain canal unit for use in stackable containers that provides circulation of water within a container assembly.
