Daphnia Culture – How to Raise Daphnia

What would it be like to have your own Daphnia, also known as water fleas? These plankton-like freshwater snails can grow up to 3 millimeters long. These adorable little creatures can be seen swimming almost vertically within their tank. They live quite happily in large groups within a tank, so that you can harvest them when you need them to feed your fish, tadpoles, salamanders, newts, or aquatic insects.

We’ll be covering everything you need about the tiny Daphnia to ensure you have a steady, fresh, and successful food supply.

Setting up a Daphnia Tank

Daphnia can be kept in small tanks up to 5-6 gallons. They can also be kept in larger tanks up to 360 gallons. The main thing to look for in a tank is a greater surface area than depth. This allows them to mimic the natural environment of freshwater habitats like ponds. A store sized 360-gallon tank used to cultivate thousands of Daphnia for hundreds of fish measures six feet long, four feet wide, and only two feet tall. You should choose smaller tanks that aren’t as deep.

It’s more than just setting up a tank. They thrive on freshwater plants such as duckweed, shrimps, or snails, as well algae. Daphnia keep the water clear just as saltwater shrimps. However, when you have many of them, the water can appear much darker than it really is. They prefer to live on the top of the water, particularly the babies and the juveniles.

Water temperature should be kept at 68 degrees Fahrenheit (20° Celsius). Freshwater plants like duckweed can be added, too. A Wonder Shell is a great way to increase the electrolyte and mineral content. It adds hardness to the water and is also a dechlorinator.

Chlorine kills Daphnia, so make sure you properly condition your water first. At least once per month, change the water and then take out half the tank to get fresh water. You can add fresh fish water from another aquarium or your own pond. Better to have older water.

Daphnia are photosensitive so it helps to have a light on your tank running 24/7. Daphnia will gravitate to light.

Indoor Tank or Outdoor Tank?

Where you physically place your tank is important. Although some Daphnia owners prefer to keep their tank outdoors, it is better to bring it inside.

– Temperature – there are fewer temperature fluctuations indoors. – No mosquito larvae – any mosquito eggs that aren’t eaten by the Daphnia turn into larvae, which turn into mosquitos. You can prevent invasive species by keeping your indoor tank free of Copepods (“Cyclops”) and other species.

Tank Aeration

What about aeration. This is a confusing topic and a very popular one when it comes down to Daphnia. It is recommended to aerate your plants for a higher yield. Daphnia seem to really thrive with a coarse air stone, especially one that’s weighted so they don’t sink. Medium-sized bubbles can reach a very rapid ‘rolling boil” consistency. When you position the aeration at one end of the tank, the Daphnia can swim to the other end if they want calmer water. Water flow will be maintained by standard airline tubing. Static water is preferable to aeration. This is because Daphnia that live in streams or ponds in nature would thrive in moving water. It really helps your yields grow.

Aeration also solves another issue – keeping freshwater plants like duckweed from taking over. A space can be cleared by constant bubbles.

Shrimp and Snails

Daphnia and duckweed aren’t the only living things to have in your tank. It is a good idea to add freshwater shrimp or snails, especially if you have large tanks with Daphnia. You should choose ones that don’t prey upon the Daphnia. They will clean out the bottoms of the tanks by eating extra yeast or other microscopic particles.

Busting Daphnia Tank Myths!

There are many myths that you may have heard or read about when setting up your Daphnia aquarium. Let’s look at them one-by-one.

– Green Water Doesn’t matter

Green water is not necessary. Daphnia have a remarkable ability to clean water. They can clean up large amounts of water in as little as two days. Don’t be afraid of adding lots of food yeast or spirulina. They will eat a lot! Because the Daphnia are quick to clean up the water, the smaller the tank the more green water you will see.

#2 – Daphnia Reproduce Every 8 Days

Daphnia excel at exponential math. It only takes eight days for a baby Daphnia to grow to maturity and begin breeding. Each Daphnia can have ten children. You can have 1000 Daphnia if you have 100 Daphnia. In a week, you will have 10,000 Daphnia. You can go on and on. You could easily go from 100 Daphnia up to 100,000 Daphnia in a single month. They live for a few months.

#3 – Don’t Underestimate Food Amounts

Your Daphnia population, along with #2, is on the rise. Don’t underestimate the amount of Daphnias they eat and how quickly they reproduce. Even if you harvest daily, there are still serious breeding populations to manage.

– Handling Daphnia Population Crisis

Daphnia can breed quickly and in large numbers so you might experience population crashes. This is especially true of smaller tanks. A larger tank can handle more Daphnia wastewater, so it is better to have a bigger tank. At most, you would need a 55-gallon tank.

What can I feed Daphnia

In their natural pond habitats, Daphnia feed on algae, bacterial flora, and other tiny plankton creatures even smaller than themselves. You will however feed active dry yeast to them in your tank. Yes, this is the same stuff used to make bread! This is a semi-dormant type of cake yeast. To activate the cultures, mix the yeast and a little water. An immersion blender may be more convenient than hand mixing. You are now ready to eat Daphnia foods.

Spirulina powder can be added to your Daphnia aquarium. It is an algae superfood that makes the water green.

How often should you feed Daphnia? This depends on the condition of your tank’s water. Once the water is clear, that’s when it’s time to feed. Sprinkle the yeast mixture over the surface. The Daphnia become very active at feeding times.

Daphnia also likes algae so grow some green plants around the tanks.

How to Harvest Daphnia

It is easy to remove your Daphnia live from your aquarium to feed your fish or other aquatic animals. All you will need is a handled fine mesh aquarium strainer net and a container to put the Daphnia in.

To get as much as possible, gently scoop the strainer through the high density Daphnia at water’s surface. These Daphnia are a light brown in color, so you will see a lot of them in the bottom of the net. To remove any remaining water, gently lift the net from the tank. Be gentle and only scoop through the water a few more times. Stick to the surface of the tank.

A few small scoops can yield a surprising amount Daphnia. They are so small. Once you’ve harvested your Daphnia, you can transfer them directly to the fish tank for feeding or put them in a tiny water jar for fish feeding within the hour or so.

Harvest a lot! It won’t kill a population if you harvest as much as possible. They will only reproduce quickly. Actually, harvesting often helps to avoid crashes and makes life easier for the Daphnia.