The invention relates to artificial fish reefs and discloses a cave conglomerate. The cave conglomerate comprises a cylinder-shaped base block, wherein a plurality of dried slanting rods are fixedly connected onto the sides of the base block; a plurality of branch slanting rods are arranged on the dried slanting rods; a plurality of cave groups are arranged on the branch slanting rods and comprise a plurality of first plastic bottles which are provided with upward bottom ends and are free of bottle bottoms; inner cavities of the first plastic bottles form caves; and open bottom ends of the first plastic bottles form cave openings. The invention provides the cave conglomerate which can be made of wastes conveniently, and is convenient to recycle and good in protection property, and the problems that conventional fish reef construction consumes effective resources, and is free of effective cave or difficult to manufacture a dense quantity of caves are solved.