San Francisco Bay Brand Freeze-dried Tubifex Worms is a nutritious high protein fish food with an appealing flavor your fish will find irresistible. It is the perfect choice for small to medium sized freshwater fish, discus, and amphibians. This food is in the form of a cube which allows it to be stuck to the inside glass of your aquarium to create a feeding frenzy that is fun to watch. Freeze-dried tubifex worms are all natural and easy for fish to digest, so they produce less waste and your aquarium stays cleaner.