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care sheet, microworms -

Care Sheet: Microworm (panagrellus spp)

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Harvesting and Use

Microworms are most commonly known as a very easy to culture live food in the aquarium hobby. These are nematodes that live on starchy environments that are rich in living yeast. They are most suited for feeding young fish fry that need very small food.

Species: Panagrellus spp
Common name: Microworm
Group: Nematodes
Size: 1.5mm in length.
Lifespan: 20-25 days (as individuals)
Diet: Active live yeast.
Appearance: Very tiny white worms. Will appear as glistening movement inside an active live culture. 

Housing Back to Top

Our recommended size: Jars or takeaway containers with a tightly fitting lid. The lid does not need holes for air, so long as the container is opened once or twice a week.
Temperature: Room temperature. Can tolerate a wide range, down to near freezing. Avoid temperatures warmer than 28C. 
Substrate: Food substrate of moistened starch (instant potatoes, oatmeal, bread, wheat flour or cornmeal) enriched with live active yeast, such as baker’s yeast.

  • Start a culture by lining the bottom of the container with moistened starch. Sprinkle very lightly with active baker's yeast, and place in a spoonful of a Microworm starter culture. The microworms will feed on the baker’s yeast that live in the starchy substrate.
  • The microworms will reproduce quickly in a matter of days. 
  • No maintenance is generally needed, a culture can last from 2-6 weeks depending on conditions. To extend the lifespan of the culture, stir the food substrate once a week and keep in a cool place. Check for any mold and scoop out any if found. 
  • Keep more than one culture at a time in case one suddenly dies off. New cultures can be started by scooping in food substrate from an active microworm culture. 
  • It is normal for cultures to smell sour and unpleasant. If the culture starts going dark and smelling differently, it may be time to start a new culture. 

Harvesting and Use Back to Top

Microworms are ready to harvest when they are crawling up the sides of the container.

  • To harvest them, simply swipe a finger across the sides of the container where the worms are. If you are squeamish about touching microworms, wearing gloves or covering your fingers with plastic wrap may help you. 
  • You may dip the worms on your finger directly into an aquarium with fish ready to feed.
  • Microworms can be pre-washed by dipping your finger into a cup of clean, dechlorinated water, then strain it through a brine shrimp net or coffee filter to catch the majority of the worms. The worms can then be fed to fish by dipping the net inside-out in the aquarium.
  • If many worms are being left on the bottom of the aquarium, scale back the amount you feed to your fish and siphon the uneaten worms to avoid fouling the water.

Microworms are very tiny and will sink, they are generally suited for young fish fry that are free swimming and able to eat sinking food items. It’s recommended to feed fish in a bare bottom or fine sand aquarium, as microworms can sink between gaps in gravel where fry cannot reach.