Formulated for Suckermouth type Catfish, Zoo Med's Pleco Banquet Block contains algae and wood fibre that is required for long-term health of your Catfish. Ingredients include shrimp, calcium, spirulina algae, and natural wood cellulose. Can be used for saltwater or freshwater fish. Block lasts up to 1 week for 2-3 small catfish or 1 medium to large catfish.