Raising Daphnia

by Bill Childers

First published in Fincinnati, the official newsletter of the Greater Cincinnati Aquarium Society

Key elements in the proper care of aquarium fishes would include water quality, space, temperature, fish compatibility and food. Just "feeding the fish" is easy - buy a can of flakes or pellets at a shop and be done with it. However, a thoughtful Aquarius will go beyond this most basic feeding philosophy and at least buy two types of dry food - one for morning and one for evening. Perhaps he will even buy a package of frozen shrimp for an occasional treat. Most aquarium fish will survive with such a feeding program. After all most commercially prepared foods are carefully made with fish nutrition in mind - emphasis on "most". I once bought a can of green flakes formulated for herbivores only to see on the ingredients list that animal fat had been used as a binder! If you want to take that extra step toward maintaining your fishes' health - try a live food. Live foods can provide that extra boost that moves you from "keeping them alive" toward "enticing them to breed".

One of my favorite live foods is Daphnia. Daphnia are freshwater "bugs" that are sometimes called water fleas because of their shape, size and jerky motion. Daphnia are easy to culture if you understand their requirements. They nourish themselves by filtering small edible stuff out of their water habitat. What kind of stuff? Just about any kind of plant or animal life form that is small enough and moves about or is suspended in their water. Thus, requirement number one is, do NOT put a filter in the Daphnia tank. I do use one airline, bubbling slowly. When the tank is dark the Daphnia seem to go to the bottom and become inactive which is bad for Daphnia production, so rule number two is to give them some light 24 hours a day. Daphnia need a reasonable temperature to be happy and multiply. Since my Daphnia tank is close to the floor, I keep a heater in it set at 72 degrees F.

I feed the Daphnia as follows: mix one package of dry active yeast with one cup of soy flour. (Kroger carries the soy flour). Once or twice a day I stir 1/4 teaspoon of this dry mixture into a cup of warm water. I pour this into the Daphnia tank, which clouds the water. When the Daphnia have made the water clear again by filtering out all the food, it is time to feed them again. Overfeeding will cause a crash. Crash = all dead. Experience will teach you how much to feed. I also keep some large ram horn snails in the tank which I feed a lettuce leaf once or twice a week. The snails produce infusoria, which is more food for the Daphnia. If you must be gone for a few days, just throw in a couple of lettuce leaves and the bugs won't starve while you are gone. The snails are also a good indicator of water quality. When water quality is really bad (a crash is at hand) all the snails will go to the top of the tank. With heavy feeding it doesn't take long for nitrates to reach a lethal level, but this can be prevented by proper harvesting. Never harvest by just netting out the Daphnia. Instead, siphon them into a bucket through a shrimp net, refilling the tank with clean water. The quantity of water to remove depends on the size of your Daphnia tank. Also, about every 10 days the mulm should be siphoned from the bottom of the tank. If you don't it will soon be crash time again.

You can size the Daphnia by pouring through different size fish nets, thus separating the smaller food for your smaller fishes. One advantage of Daphnia is that they will remain alive until eaten instead of polluting your tank.

Belonging to an active fish club is almost a requirement for year round feeding of Daphnia. Why? Because when you get lazy/stupid and crash your Daphnia culture you can ask a member to bring you a new start to the next meeting. Thank you Tom, Greg, Charley and others! Keeping two tanks going is another good idea.

For lots of information on numerous live foods, refer to Charley Grimes' chapter in the book ENJOYING CICHLIDS. This is a great book!

This article may be copied and distributed at will as long as you give credit to the author and send me a copy of any publication that uses it.

May your friendships and fishes remain healthy and multiply.

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