The holiday block with real fish food inside! Automatically feeds your fish for a whole weekend. Place the 3-Day Pyramid Fish Feeder in your aquarium and 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. One pyramid will feed 15 to 20 average sized fish in a 40 litre aquarium for 3 to 4 days, depending on the temperature and pH of the water. Suitable for tropical, coldwater and marine fish.