On the whole, microworms are one of the most dependable and simplest of the live foods you can culture. With a minimum of attention, you, too, can have live food for your juvenile fish and fry, whenever you need it.
Nearly every aquarist, it seems, has a different recipe to culture microworms, but basically you need: a starter culture (available commercially, or from a fellow aquarist); a culture medium; water; regular baker’s yeast; and a suitable container.
Any appropriate plastic or glass container with a lid (to keep moisture in and pests out) is suitable for microwormsplastic cups, cottage cheese or margarine containers, plastic shoeboxes, etc.
The culture medium should be starch based. Most cultures are based on baby cereal (Hi-Protein, Rice, Oatmeal, etc.); instant mashed potato mix; or regular flour; but any good breakfast cereal without fruit will also work; as will cooked porridge; or a mix of cornmeal and whole-wheat flour. Some aquarists successfully raise microworms on well soaked white bread.
Add water to the culture material and mix it to make a thick slurry. Place 1/2″ to 3/4″ of the culture medium in the bottom of a suitable container, add a pinch of yeast and the starter culture and mix well. Put a cover loosely on the container and place where it will be moderately warm, 70-75F or so.
Wait a few days, then check the culture for activity. The culture is “working” properly when the surface shows a ripply, satiny appearance.
There are almost as many variants to collecting microworms for feeding to your fish as there are culture media. Among the recommended methods:
With your finger or a spoon, scrape off the layer of worms that have crawled up onto the sides of the container.
Soak a popsicle stick in water, then insert it into the container. The worms will crawl up onto the wood.
Or simply scrape off a bit of that top “working” layer. Any extra nutrients in the fry tank from the culture media will help support a culture of infusoria.
If you want to get a bit fancier with your microworm culture you can put the culture medium (Roger Sieloff uses flour and water) into glass jars, then use an autoclave to set the culture medium, drive off any chloramines, and sterilize it. Once cool, inoculate with starter culture. This method will produce a culture that will last approximately 3 weeks.
Since cultures will not continue indefinitely, most aquarists maintain several cultures at one time, and start new ones regularly. In addition, they add new culture media and/or yeast from time to time to keep existing cultures in production longer.
Several problems are often encountered with microworms: limited culture life, cultures going bad (souring, liquefying, or drying out) and dirtying of the tanks where they are fed.
To prevent your microworm cultures from failing completely, keep several cultures going at once, and start new ones on a regular basis. To avoid cultures drying out, keep the top covered before and after feeding, and occasionally stir in a little additional water. Be sure to use water with the chlorine removed, or a bit of tank water.
Sour, “funky” cultures can sometimes be revived by the addition of fresh media and yeast. For a discolored culture, scrape off the darkened top layer first. One aquarist suggests adding a pinch of baking soda when the culture gets “funky.” Occasionally, a culture will “liquefy,” with the top surface turning thin and runny, or developing a “skin”. Sometimes such a culture can be revived; sometimes nothing will help.
Some “dirtying” of tanks is inevitable when feeding microworms by all but the popsicle stick method. In most cases, this causes little problem, and actually benefits fry by providing nutrients for infusoria. To deal with the additional dirt, you may have to add a couple of snails, or step up your schedule of partial water changes.
— G.C.K.A. Newsletter, August 1997