How to Culture Microworms For Fish Fry

How to Culture Microworms for Fish Fry

Because of their attractive movements, live foods can be very useful in breeding fish. They encourage babies to eat more and grow faster. However, certain fish like betta fish, rainbowfish, and ram Cichlids can produce small offspring that aren’t big enough to eat traditional fry foods such as crushed flakes or baby brine shrimp. You can instead start a micro, walter, or banana worm farm to keep the babies happy.


What are Microworms and How Can They Help?

Microworms are nematodes or roundworms found in the Panagrellus Genus. The most popular types used in the aquarium hobby are (in order of smallest to largest):

– Banana worms (Panagrellus nepenthicola) – Walter worms (Panagrellus silusioides) – Micro worms (Panagrellus redivivus)

They can be as small as 1-3mm in length, and 50-100 microns wide. This is slightly larger than vinegar eels. (By comparison, newly hatched brine shrimp are 450 microns in size, so even the tiniest fry can slurp down nematodes like noodles.) When they reach maturity, female roundworms are usually 3-4 days old. They can produce 300 to 1000 live young each year, depending on which species.

Close-up view of starter cultures for micro worms and banana worms

How to Start a Micro Worm Culture

The care requirements for micro, walter and banana worms are nearly identical. Therefore, the remainder of this article will not be applicable to white or grindal worms. These worms are annelids and require a different type of setup.

1. The following materials are required:

– Starter culture of banana, micro, or walter worms (purchased from a fish club auction, local fish store,, or other online source) – Box of plain instant mashed potatoes (without any extra flavoring) – Several small plastic tubs or deli containers, about 5 inches (13 cm) in diameter or larger, with taller sides and tight-fitting lids – Dechlorinated water at room temperature

1. To cover the bottom of your plastic container, add a layer of mashed potato chips measuring 0.5 inches (1.5 cm). Keep adding a little bit of water and stirring the mixture until you get the consistency of light and fluffy mashed potatoes. The mixture shouldn’t be too dry or crumbly, nor too wet and soupy.

Note: In our experience, adding yeast does not seem to help or hinder the growth of the culture. Instant mashed potatoes or baby rice are preferred over other types of cereals because they don’t emit a strong smell like oatmeal.

1. After the mixture has been incorporated into a container, spread it out evenly. Then add a tablespoon of starter worm cultures. Place the worms on the medium.

1. Use a razor blade to cut a small hole in the lid (approximately 0.5 cm x 1.0 cm) so the roundworms can breathe. Tape or stuff the hole with a piece of filter floss. This stops flies and other pests from getting into the container. Cover the container.

Notice: Some people prefer to cover all of the holes in the lid with a pillowcase, even if they are making a bigger worm culture.

1. The date you created the culture, along with the type and number of roundworms used, should be labelled. The container can be stored at room temperature. 2. For the event that one of your cultures fails, you can repeat steps 2-5. It is possible for the medium to become moldy, spoiled, infested with bugs, or full of worm waste.

How to Harvest Microworms to Feed Fish

Some worms may climb out of the medium onto the walls and make it easier to collect them. To clean the sides and bottom of the plastic tub, use your fingertip or a cotton swab. Dunk the worms directly into the tank to feed the fish. The micro worms live approximately 8-12 hours in water, so do not overfeed to avoid water quality issues. It’s okay if a little potato mixture gets into the aquarium because the omnivore fish will eat it along with the roundworms.

Hobbyists have discovered that microworms fed alone can lead to deformities in fish, whether from nutrient deficiencies and water quality issues. So make sure to add high-quality food like Hikari First Bites, Easy Fry, and Small Fish Food to your fish’s diet.

How to Maintain the Micro Worm Culture

As the culture ages, it becomes more and more full of worm poop, which makes the medium runny. Make a new culture by repeating Steps 2-5 from the above section and adding one spoonful of worms from the old culture. Because of the high nutrition, protein, and fat content, we recommend switching to live baby brine shrimp when the fry reach sufficient size. Find out how to make your own brine shrimp by reading the article linked below.