Culturing Daphnia in a Few Easy Steps
This is the inspiration you need to get started with live food culturing. Daphnia are very
interesting creatures, but they are also easy and fun to culture under the right condition.
Daphnia (daff-NEE-ah) are small freshwater crustaceans that are found on just about
every continent in the world. From the frozen artic to vernal desert pools, daphnia
occupy an important niche at the lower rungs of the food web. Most aquatic insects,
amphibians, invertebrates, fish and fowl utilize daphnia as a food source. And what an
excellent food source they are! Daphnia are high in protein, vitamins A & D, and
indigestible chitin (KITE-un) to aid in digestion.
Daphnids have an almost bulletproof reproductive strategy. They have the ability to
rapidly clone themselves asexually when conditions are right. When conditions
deteriorate, they have the ability to procreate sexually and produce resting cysts that
can hatch when conditions improve.
Daphnia are truly hard to beat as a live food culture for tropical fish, mostly because
they are so prolific and easy to culture. There are as many ways to culture these little
crustaceans, as there are people that culture them. It really is hard to go wrong with
these critters. Here are the steps to culturing daphnia:
1) Set up your green water cultures
In a pinch you can feed your Daphnia a very, very small pinch of flour or a single grain
of oatmeal. Stir the container and the Daphnia will filter feed the dissolved food in the
water. But the best food for rapid growth is green water or single celled algae.
Take some clean plastic storage containers or old used aquariums, and place them in a
spot outdoors that gets plenty of sunlight, but not too much direct sun. Fill the containers
with some gunky water vacuumed from your fish tanks, and toss in a pinch of natural
fertilizer such as blood or bone meal. Some daphnia culturists report having good luck
using dissolved Miracle Grow at the rate of 1 teaspoon per gallon of water. An old gallon
milk jug is perfect for dissolving the mix. Add in some lettuces and let it rot.
Set up at least two green water containers before you buy your starter culture of
daphnia. Allow the green water cultures to become emerald green in color. It’s a very
good idea to have duplicate cultures going just in case one of them crashes.
What good is it to take a few weeks storing up a bunch of green water only to have it
eaten by the daphnia in a few days? As a rule of thumb, set up at least three times more
green water than you need to house your daphnia in. With a couple of containers
equaling twelve gallons of green water, you can safely plan on supporting four gallons
of daphnia culture. A single gallon container of water can support hundreds of daphnia.
2) Prepare for the arrival of your daphnia culture
Once you have plenty of emerald green water, it is time to transfer some green water
culture to the containers that will house your daphnia. To keep a constant supply of
green water going, be sure to replace any green water you transfer out of the green
water container with tank water or dechlorinated tap water. Try not to use all of your
green water up, since it is much more work to start a new culture than it is to keep an
existing one going.
For housing daphnia cultures indoors, plastic shoe or sweater boxes work well as does
the standard ten-gallon tank. Outdoor cultures do well with 55-gallon drums, plastic tubs
or kiddy wading pools. Just about anything that holds water and isn’t toxic can hold
daphnia.
It is also a good idea to set up some smaller cultures with a number of different water
conditions and different types of containers. Pint-sized drinking water bottles or 2-liter
soda pop bottles work well in a pinch. The idea is to hedge your bet by placing your
daphnia culture in green water, spring water, treated tap water and whatever else you
can think of, to assure that at least some of the daphnia will survive. There is a remote
chance that your new arrivals may not take to your green water or your containers may
not be daphnia safe. It is better to be cautious by not putting all your eggs in one basket.
3) Acclimate and release the daphnia
Open the shipping box immediately. A few dead daphnia in the shipping bag is normal.
If you notice a marked difference between the temperature of the shipping bag and that
of your water containers, you should float the bag for 10 to 15 minutes to equalize the
temperature a bit. If both are relatively the same, you can just start divvying up the
daphnia amongst the various containers at your disposal. Add a few daphnia at a time,
very slowly. Do you see any instant deaths? Don’t put any more daphnia in a container
that has them sinking to the bottom to die. Keep divvying them up until they are all
spread out among a number of water containers. A dedicated fish room eyedropper
works well for transferring the daphnia.
4) Check on your cultures daily
So your new daphnia culture made it through the night in your green water? Good for
you! You can start consolidating your mini-cultures into the green water until you have
at least two cultures. Again, multiple cultures will help hedge your bet should one of the
cultures crash. You will have learned whether daphnia can live in your treated tap water,
which is good to know. Daphnia are so sensitive to toxic water that they are used in
industry to test for water pollution, sort of like canaries in a coal mine.
Check daily to make sure they have enough green water. Add more as needed, and
remember to replenish any outdoor green water containers accordingly if you have
them.
5) Care and feeding
If the daphnia eat your green water too fast you may need to set up another green water
culture. Daphnia will also eat powdered fish food flakes, bacteria-laden water, and even
infusoria from snail droppings. Hikari “First Bites”, “Liquifry”, “Spiralina Powder” and
“Cyclop-Eeze” are great foods to supplement your green water as well. Care must be
taken not to over feed or pollute the daphnia culture water.
Daphnia populations are known to pulse (rise and fall). A lot depends on water quality,
available oxygen, light duration, and available food sources. Some trial and error and
experimentation is in order with regard to light duration, added air bubblers and amount
of food to offer. By and large, leaving the light on all the time will help promote algae
and bacteria in the culture, and an air bubbler (no airstone!) will keep water circulating.
The ambient temperature should be kept in a range that is comfortable for people.
Outdoor cultures can be pretty much left to their own devices.
If you fear your culture is crashing (you start to see a lot of dead daphnia), remove 10%
of your culture water. Then add fresh conditioned water and some food to the container.
Also, harvest some of the daphnia to start a new culture, and/or provide a heavy feeding
for your fish.