The Api 7-day Pyramid fish feeder is suitable for both coldwater and tropical fish and contains real food that automatically feeds your fish when you are on holiday. Feautures: Contains real food pellets to nourish your fish. Has a secret food chamber with spirulina algae that opens half way through its life. Pack contains 1 pyramid which will feed 20 average size fish for up to 10 days. To use simply place the pyramid fish feeder in your aquarium. It will immediately start to dissolve, giving off a stream of fine bubbles. Within a few hours the first nourishing food pellets will begin to swell and push out of the pyramid. On about the 4th day the secret chamber will open releasing the spirulina cube for a surprising mid week treat. Not to be used in goldfish bowl or aquariums without adequate filtration.