Daphnia, commonly known as water fleas, are small planktonic crustaceans that are easy to culture and highly nutritious for fish. To culture daphnia, use a container with aged or dechlorinated water, provide moderate aeration, and maintain a temperature of 18–24°C. Feed them yeast, algae, or powdered spirulina. Regular water changes and avoiding overfeeding ensure a healthy population. Daphnia reproduce rapidly under optimal conditions. A complete natural protein source for your fishy friends.