Zoo Med Laboratories AZMBB6 Plankton Banquet Block Feeder Giant 2-Count (Two 1-unit cards) A time-released Giant Plankton Banquet Block will feed approximately 15-20 average sized aquarium fish for 10 to 14 days Freeze-dried plankton and blue-green spirulina chunks are great for bottom feeders Giant Plankton Banquet Blocks will not cloud water; great for fresh or saltwater fish Do not use this product in fish bowls or aquariums which do not have aeration or filtration