Microworms are a small roundworm or Nematode, about a millimeter or two in length. They are fed to fry typically a day or two after first hatching.

They are cultured in cereal in small containers and may be the easiest to grow of all live foods.

Simply take a small plastic container, such as a margarine tub and add cereal, either cooked or dry. If you use dry cereal you'll need to add enough water to make a thick paste; if cooked it should be of this consistency. Oatmeal can be used, either the regular breakfast kind, or, baby food cereal. The high protein variety, if available in your area, is probably the best.

Inoculate it with a stater culture. Sit back and wait. In a few days to a week, you'll see a wiggling mass crawling up the sides just above the cereal. They can be collected with a paint brush, or just wiped off with your finger.

In a week or two, the culture will become more liquid and will eventually smell really bad, so you should probably start cultures periodically - they don't last forever, three weeks is about all you'll get out of one.

Sometimes they can be rejuvinated by simply dumping the culture out and adding new medium. The microworms that get left behind are enough to inoculate the new media.

Some people add a pinch of yeast to the media which prevents it from fouling as quickly. I've personally had problems with yeast anywhere near aquarium water - it seems to form long sticky white threads and gets in the fishes gills causing distress and death. Apparently this is not universal as some people have success, but forewarned is forearmed.

Microworms can also be frozen and thawed successfully; get an ice cube tray and freeze a culture in small cubes and you'll never run out. You might want to put this in a plastic bag and label it well as fish food lest it be thrown out by unsympathetic and surprised family members.