An aquarium fish partition device separates an aggressive fish from other fish within an aquarium. The device includes a base, a top, and an inner perimeter wall extending between the base and the top defining a central interior space. An outer perimeter wall extends between the base and the top defining a medial space between the inner perimeter wall and the outer perimeter wall. Each of a plurality of slits extends through the inner perimeter wall wherein the central interior space is in fluid communication with the medial space. Each of a plurality of slots extends through the outer perimeter wall wherein the medial space is configured to be in fluid communication with an area outside of the outer perimeter wall. The slits are offset from the slots such that the inner perimeter wall and the outer perimeter wall are configured for retaining a fish in the central interior space.
