Infusoria 
By Bill Malay Reprint from THE AQUARIAN

Here's a proven method of culturing Infusoria for raising the fry of your egg layers. With this method, a one-gallon culture will support about one hundred young fish until they are past the Infusoria stage.

There are ways to raise the fry of egg layers that require infusoria as their first food. One of the main reasons most of the newly hatched fish disappear is that, when Infusoria is fed, there is too much of the contaminated water in the tank, thus killing the fry.

The materials needed are at least two test tubes, a one gallon wide mouth jar, a quart jar to stand the tubes upright in after they are filled with Infusoria water, a syringe bulb with rigid plastic tubing inserted in the open end of the bulb, and some lettuce leaves. The water used is taken out of a tank that has aged water and fish in it. The method used is as follows:

Fill the one gallon jar with the water from the tank, and add 1/2 dozen lettuce leaves. In about 3 days, you will notice a scum forming in the jar. Next, take the syringe and suck the water and scum from the top of the jar, not going in deeper than 1/4". Now take a handkerchief, or bleached muslin, such as an old sheet, and strain the water taken from the jar of Infusoria through the handkerchief into a small jar or cup. This removes most of the scum particles.

Fill the two test tubes with the strained water and stand them upright in the jar over night. The next morning you will notice that the Infusoria has risen to the top of the test tubes. Pour only about 1/2 inch of this into a tank that has fry in it and pour the rest back into the Infusoria jar.

Do not put an airstone into the gallon jar as this would keep them swirling in the jar and they would not collect in the top in a mass as you want them to. My theory is that the reason the Infusoria collect in the cultured jar, and also in the test tubes, is that they come up for oxygen.

This amount of Infusoria culture that you have in the jar will smell foul, but that does not harm your fish as you harvest almost pure Infusoria each morning and night until the fry are ready for Microworms or other food. A 1 gallon culture will support about 100 young fish until they are past the Infusoria stage.

Keep looking at the bellies of the fry to make sure that they are full at all times. A magnifying glass is very helpful in checking the young fry and also to see how much Infusoria is already in the tank with them.