General Information of Daphnia Magna
Daphnia Magna is a small planktonic crustacean with the scientific name Simocephalus exspinosus (Koch, 1841). Daphnia has gregarious behavior. During daylight, Daphnia stays in the safety of deep water and feed at the surface only at night. Daphnia is found in lakes, rivers, and temporary water sources in North America and Europe, such as the United States, England, and Belgium. Daphnia can live in both fresh and brackish water.
Biology of Daphnia Magna
- Average age: 56 days
- Adult size: length 3-4 millimeters
- Newly-hatched size: length 0.40-0.49 millimeters (400-490 micrometers)
- Reproduce after 6-10 days of age
- Both lay eggs and give live birth
- One female Daphnia gives birth to an average of 50 offspring
Start to culture
Prepare the necessary equipment
- Daphnia eggs
- Tray [0.1 gallons (0.38 liters) in size for hatching]
- Tank [size should be a minimum of 3 gallons (11.3 liters) for culture]
- Aquarium air pump and aquarium air control valve
- Aquarium fishnet
- Aquarium heater or heat lamp
- Aquarium siphon cleaner tube
Recommended water source
- Tap water is an easy and popular choice, as long as it has been treated to remove chlorine and adjusted condition properly.
- Freshwater from your aquarium
- Bottled water. It is the most expensive way. The mineral water is not recommended because the mineral level is too high.
Recommended water condition
- Ammonia level is less than 1.5 milligrams per liter.
- pH between 6.2 and 8.9 (pH 7.8 is optimum.)
- Low in salinity (fewer than 8 grams per liter)
- Do not use any chemicals.
Optimize the environment
Place a heat lamp above the tray for hatching. Place a heater inside the tank to keep the water temperature between 70 and 90 °F (21 and 32 °C). Put an aquarium thermometer in the tank to monitor the water temperature. If you live in a place with suitable temperature ranges, the heater may not be needed. If the temperature is low, it will take an additional 3 to 5 days for hatching. Hatching place is important. It is best to hatch inside to prevent invasive species and keep the temperature steady.
Sunlight is good to increase hatching capacity. Let the eggs receive sunlight 3-4 hours per day in the temperature range. Be careful overheating. If sunlight is not available, you can use the lamp instead. The eggs still hatch even though they do not receive sunlight.
Hatching Daphnia Magna
Fill up the water into the tray. Open the capsule carefully to sprinkle the eggs into the water. Make sure that the eggs do not accidentally get stuck on the edge of the tray. Floating or sinking eggs do not affect with hatch rate. After sprinkling the eggs into the water, it will hatch within 3-10 days.
Add oxygen to the water. In the early days, adjust the air control valve to the lowest level because Daphnia is very small and may lose control in swimming. Gradually adjust the air control valve to the level that suits the population of Daphnia.
Look closely. Daphnia is so small and almost invisible to the human eye for the first few days. You can use a flashlight in the dark to confirm the hatching. Shine lights on the water surface and watch the shadows move.
After 3-10 newly-hatched appear, that means the eggs begin to hatch. Then transfer the Daphnia and eggs to the tank for culture by pouring the hatching tray into the tank and add the water.
If the eggs do not hatch
If the eggs do not hatch within 10 days, dry the eggs by pouring them into an aquarium fishnet and wait for 2-3 days. After the eggs dried, start the hatching process again.
Daphnia Magna food
Daphnia eats bacteria, yeast, Spirulina, and Chlorella.
Feed Daphnia by pouring the prepared food into the tank. if you feed them by Chlorella the water will turned to light green. Be careful to overfeed. Feed 1-2 times per day. Increase or reduce the food according to the population of Daphnia. Do not feed more if the water is still green. In a few days, they will start to reproduce, and you will have thousands of them to feed your fishes.
Change the water
The water will gradually turn light yellow due to the waste excreted by Daphnia. Drain the water by using an aquarium siphon cleaner tube. Suck Daphnia and water out as much as possible from the water surface to downward.
Pour the water and Daphnia into a bucket through an aquarium fishnet. Daphnia will get stuck on the fishnet. You do not have to suck the Daphnia that sinks to the bottom of the tank. It is dead, Drain the remaining water and dead Daphnia out and clean the tank.
Add 80% of fresh water and 20% of old water into the tank. Then, drop the Daphnia on the fishnet into the water. When the water turns dark yellow, it means a lot of waste is in the water. The waste will turn to be ammonia and kill Daphnia, so keep your eyes on the color of the water.
Feed Daphnia Magna to your fish
Use syringe, dropper, bucket, or aquarium fishnet to transfer Daphnia to your aquarium. If the population of Daphnia in the tank is too dense, you can freeze some of them. Live Daphnia is great food for your tropical fish. We highly recommend it. It is simple to grow if you follow the tips above. Your fish will love eating it.