Daphnia are small freshwater zooplankton that have been used as aquarium food since the early beginnings of the hobby. Today they are still widely used in Europe and Asia for feeding both freshwater and marine tropical fish. They are an excellent food source for raising young fish, and larger fry. Ingredients: Daphnia, Daphnia sp., water sufficient for filling and freezing, Potassium ascorbate. (source of Stabilized vitamin C).