Culturing Daphnia | A Nutritious Live Food for All Stages

Daphnia, often called “water fleas,” are a favourite live food among aquarists, including myself! Their jerky swimming motion triggers a strong feeding response in fish, and their size range makes them suitable for fry, juveniles, and adults alike. Rich in protein and fibre, Daphnia also help clear out excess nutrients in tanks when used thoughtfully.

Best of all? They are surprisingly easy to culture at home with just a few basic supplies.

What You’ll Need:

• Clear container a bucket, tub, or aquarium work well
• Dechlorinated water
• Daphnia starter culture
• Air pump with airline tubing and gentle sponge filter (optional but recommended)
• Light source (indirect sunlight or aquarium light)
• Food source (see below)

Prepare the Culture Container

1. Choose your container: A bucket, tub, or aquarium. 20L+,(my prolific is culture is in a small pond).
2. Add water: Fill with dechlorinated tap water or rainwater. Avoid distilled or RO water as it lacks minerals your Daphnia need.
3. Aerate gently: Add an air stone or sponge filter to keep water oxygenated and prevent stagnation. Gentle rolling bubbling, too much turbulence can harm the Daphnia.
4. Lighting: Place the container in a spot with indirect sunlight or use a low wattage aquarium light. Daphnia are phototactic, so they will gather near light, which helps with harvesting.
5. Add leaves: Toss in a handful of dry leaves, banana leaves work especially well. As they break down, they create a natural biofilm that Daphnia graze on, enriching the culture and supporting long term health.

Add the Daphnia Culture

Introduce your starter culture into the prepared container. If shipping delays occurred, acclimate slowly by adding small amounts of your culture water to the starter over 30 minutes.

Feeding Your Daphnia

Daphnia are filter feeders, so they feed on microscopic particles, the goal is to create a gentle bloom of suspended food in the water column for them to consume.

Common food options:

• Green water (algae): Ideal if you have a separate algae culture.
• Yeast mix: Dissolve a pinch of active dry yeast in warm water and add sparingly.
• Spirulina powder: Mix a small amount with water and pour in.
• Soy flour or powdered fish food: Use very lightly to avoid fouling.
• Rice water: Save your water when washing your rice before cooking and pour in.

Tip: Feed lightly, cloudy water can mean overfeeding. Daphnia thrive in clean, lightly tinted water.

Conditions & Care

• Temperature: 18°C to 24°C is ideal for reproduction, however will live out of this range. 
• pH: Neutral to slightly alkaline (6.5-7.5)
• Water changes: Replace 10 to 20% of the water weekly with fresh, dechlorinated water.
• Avoid predators: Keep snails, fish, or hydra out of the culture container.

Once your culture is thriving (usually within 1-2 weeks), you’ll see clouds of Daphnia pulsing through the water and at the surface.

To harvest:

• Use a fine mesh net or turkey baster to collect Daphnia.
• Rinse briefly in clean water to remove excess food particles.
• Feed directly to your fish and watch them go!

Splitting & Backup Cultures

To keep your supply steady:

• Split cultures every few weeks into fresh containers.
• Backup cultures are helpful in case of crashes due to temperature swings or overfeeding.
• If the water smells foul or Daphnia numbers drop, refresh with clean water and reduce feeding.

Daphnia are a fantastic, sustainable live food that supports fish health and tank balance. Culturing them at home not only saves money, promotes breeding of lots of fish they also connect you more deeply to the rhythms of aquatic life.