Description Allows aquarium fish to graze or nibble as needed when hungry vs plaster feeders that dissolve. With whole daphnia and contains all essential nutritional elements to keep your fish healthy for up to 5 days. Gel block doesn’t dissolve like plaster feeders and will not pollute water or negatively impact water quality. Simply remove the foil lid and pop the food out of the tin into your aquarium. Consult the Feeding Guide Chart on the back of the package and remove any uneaten food when you return.