Growing Daphnia for the Aquarium

Daphnia belong to a group known as the Daphniidae, & are close relatives of the freshwater shrimp, & the brine shrimp (Artemia). Their generic name is usually known as "water flea." This common name is derived from the jerky movements of Daphnia in the water. The over 150 different species can be present in North The united states, with a similar amount of species growing in Europe. A number of these species find common ground on both continents.

Daphnia are a small crustacean, & are great to make use of as a fresh food because they will exist in the tank water until eaten by the fish. Daphnia may even be sterilized if it is felt necessary by placing in a 5% solution of Clorox for three to five minutes. Only a few micro-organisms can survive this. Be definite, however, to rinse them thoroughly before feeding!

Daphnia can be raised both inside & outside. Plenty of people raise daphnia in a small kid's wading pool. A more controlled surroundings, however, is done inside, & can be done year round if lives in northern climes. This can be as simple as a couple of liter bottles, to a twenty gallon tub bought from a store such as Menard's. The ideal situation is to have as much oxygenated surface area as feasible, so if there is room for a bigger container, by all means use it. A shallower surroundings suits daphnia best for prolific growth.

PH levels for successful Daphnia cultures ought to be in the range of 6-8, & ought to be more alkaline than acidic. If raised outside, no aeration is necessary. If raised inside, aeration ought to be adjusted to produce large bubbles. Small bubbles in the daphnia culture will cause the bubbles to become lodged in the carapace of the culture, & they will die.

Water temperatures for Daphnia magna are not a high requirement, but the optimal temperature ought to be in the 64-72 degree range. they are tolerant to changes in temperature, & can withstand fluctuations down to freezing. In fact, Daphnia can be frozen & kept in the freezer, & then revived when needed. Moina withstand a higher fluctuation in temperature than do D. magna.
Lighting ought to be in the neighborhood of eight or more hours light per day & light intensity equal to or greater than 850 lux. A simple light & a timer can accomplish this inside.
Feeding the Daphnia is where most aquarists fail. Daphnia feed on dissolved organic matter, yeast, various groups of bacteria, microalgae, & detritus, or mulm. Organic fertilizers, such as fresh cow manure. It is not recommended by our breeder, though, because of the antibiotics & supplements fed to dairy & beef cattle. A much better mixture is a combination of tablespoon each of spirulina, soy flour, & active dry yeast, added to a pint of water. This mixture ought to be added so that the water is cloudy, but you can see the bottom clearly, & observe the Daphnia swimming in the culture. This mixture ought to be added carefully every or days, being cautious not to over feed. At this time, you ought to see an abundance of Daphnia, & they can be harvested to feed your fish.

Harvesting is simple - basically use a tiny aquarium net, observing that the smaller Daphnia fall through the netting to grow further. In this way, the adults are harvested, and can be fed to your fish. The more youthful Daphnia can go on to produce still more fish food. Harvested Daphnia can be kept in the refrigerator for several days in neat water.
Daphnia are high in protein, and a excellent diet for tropical fish. Some aquarists feed them exclusively. They provide up to 70% protein to your tropical fish, and are an excellent source of live food for the aquarium.