Tetra Marine Algaeblock is a special food for all marine fish that allows fish to graze naturally. Tetra Marine Algaeblock is a practical alternative to frozen food without the need refridgerate. Tetra Marine Algaeblock is a convenient single serving that has a patented active formula to ensure your fish has a long and healthy life. Tetra Marine Algaeblock has been created for less active species that prefer to graze and may find it hard to compete with other fish at feeding time.