Red Russian Daphnia (Daphnia magna) are an easy to culture live food for your fish. You will receive an actively growing culture. To make your culture bigger, use a bigger container and pour this culture in and use green algae water to feed them. We don't like using yeast, etc as it always seems to crash a culture. Natural is best. 100+ Daphnia per culture minimum with larger numbers common depending on time of year.