How to Culture Microworms For Fish Fry

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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, some fish (such as betta fish, ram cichlids, and rainbowfish) produce miniscule offspring that are too small to eat traditional fry foods like live baby brine shrimp or crushed flakes. To keep your babies happy and healthy, you can start a micro, banana, or even walter worm culture.

What are Microworms and How Can They Help?

A “micro worm” is a common name for a nematode or roundworm found in the Panagrellus genus. The most popular types used in the aquarium hobby are (in order of smallest to largest):

– Panagrellus nepenthicola – Walter worms – Panagrellus silusioides – Microworms – 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 contrast, the size of newly hatched brine shrimp is 450 microns. This means that even tiny fry can eat 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 of banana worm versus micro worm starter cultures

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. Add a 0.5-inch (1.5 cm) layer of mashed potato flakes to cover the bottom of the plastic container. Continue to add a little water to the mixture and stir it until it resembles fluffy, light mashed potatoes. You don’t want the mixture to be too wet or soupy.

Note: Adding yeast to the culture does not seem either to aid or hinder its growth. Also, we prefer to use instant mashed potatoes or baby cereal because they don’t produce a smelly odor like oatmeal and some other mediums do.

1. The mixture should be spread evenly into the container. Next, add one spoonful starter worm culture. Spread the worms out onto the medium.

1. You can make a small opening (approximately 1cm x 1cm) in the middle of the lid with a razor blade, hole puncher or hole saw. This will allow the roundworms to breathe. Tape or stuff the hole with a piece of filter floss. This prevents flies or other pests from entering the container. The container should be sealed.

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. Label the culture with the type of roundworm you’re using, as well as the date it was created because the cultures have an expiration date (see below). The container can be stored at room temperature. 2. To make multiple microworm cultures, repeat Steps 2-5. You should have backups in case the original medium becomes spoiled, moldy or infested.

How to Harvest Microworms for Fish Feeding

Some worms may climb out of the medium onto the walls and make it easier to collect them. Simply use your fingertip, a cotton swab, or a cheap children’s paintbrush to wipe along the sides of the plastic tub. For fish to eat, you can dunk the worms in the tank. The microworms will live between 8 and 12 hours in water. Avoid overfeeding to prevent water quality problems. It’s okay if a little potato mixture gets into the aquarium because the omnivore fish will eat it along with the roundworms.

Hobbyists know that microworms are sometimes difficult to feed. This could be due to nutrient deficiencies, water quality issues, or a lack of food.

How to Maintain the Micro Worm Culture

The culture will become more and more contaminated with worm poop over time. This makes the culture very thin. Make a new culture by repeating Steps 2-5 from the above section and adding one spoonful of worms from the old culture. We recommend that you switch to baby brine shrimp once the fry have grown sufficiently large. They are high in protein, fat, as well as nutritional content. The article below explains how to raise your own brine shrimp.