I have used the Hikari and man those things are hard as a rock. I have been considering this for my bottom feeding fish. I have no clue if it is worth anything nutritionally. Said to contain 20% Spirulina.
http://www.kensfish.com/aquarium-supplies/fish-food-feeders/sera-spirulina-tablets.html


http://www.kensfish.com/aquarium-supplies/fish-food-feeders/sera-spirulina-tablets.html

