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Microworm Culture Rejuvination

Neglected Microworm Culture in Shoebox


Microworms are an excellent food for tiny fry and are used by many aquarists off and on.  Once a batch of fry gets larger, microworms are no longer needed, and the culture often gets forgotten, unless one is breeding many species constantly.  When neglected, cultures often turn grey, become firm, and show little wetness on the surface, and, after many weeks are usually thrown away.  However, soon another batch of fry comes along and one is looking to obtain a culture again!  I contend that, instead of throwing cultures away, one should first try to rejuvenate the old one. 


Initially, setting up a microworm culture is fairly simple.  I use a clear plastic shoe box 6X12 inches with a lid.  To make sure the lid seals well, put a rubber band around the box and lid to hold it tight.  This helps to keep insects out and odors in.  Use 1-minute oatmeal right from the container (uncooked) for their food.  A layer of this oatmeal (2/3 to 1 cup) is spread thinly over the bottom of the container.  Gently moisten the oatmeal with water from a spray or squirt bottle until the surface appears slightly wet or shiny.  5-10 small dabs of an existing culture are added to the surface of the oatmeal.  Existing cultures contain growing yeast because that is what the microworms feed on, but you could add a pinch of brewers’ yeast just to be sure.  Cover and let the culture grow.  I keep my cultures in my fishroom at about 75-78 degrees and the microworms start climbing up the sides of the container in about 5-7 days and produce for about a week.  I harvest the worms by using my index finger to wipe them off the smooth sides and then dip my finger in a small cup of water which is stirred and fed to fry with an eyedropper.  Keep at least 2 or 3 cultures going at the same time to insure consistent production.


To rejuvenate the culture when production slows or ceases, I simply sprinkle a thin layer of dry 1-minute oatmeal (1/3 cup or less) over the surface and then sprinkle with water to get the surface slightly wet or shiny.  If there is life in the culture, within 6-8 hours the sides will be covered with many worms which can be harvested.  Cultures can be rejuvenated many times, but production will decline somewhat with each rejuvenation.  I have neglected cultures for a month or more and then rejuvenated them with good success.  I have not found bad odor to be a problem because the containers are tightly sealed and possibly the warmer temperatures firm up the medium and don’t allow it to get soupy.  It seems that cultures kept outside the fish room (68-70 degrees) have more odor problems, and cultures that turn dark brown and fully dry out will not rejuvenate, but it certainly is worth a try!

Harvesting microworms with finger