Although they are referred to as micro"worms", microworms are actually a form of nematode. Slightly smaller than baby brine shrimp (bbs), these nematodes are a good first food for betta fry up to about a week old. After that, the fry are large enough to eat slightly larger foods such as bbs and finely ground flake food. Microworms are also easy to keep, and extremely prolific. The down side of using them for a first food is that they typically sink to the bottom of the tank while the fry usually stay near the surface.

Getting Started

To get going you will need to acquire a starter culture. This should be easy to acquire from a fellow hobbyist if there is a betta club nearby with a lot of betta enthusiasts in it, otherwise you can purchase a culture by mail order from places like www.livefoodcultures.com. You only need a small batch to start with.

Containers

A small container that has a lid you can punch holes into is ideal. (A very small hole is sufficient, as the main purpose is to allow some air into the container). Stackable containers like the round plastic tubs that some brands of margarine come in, or the small, flat, round containers used for packaging Philadelphia cheese are great because it is easy to harvest the worms from these, and you can stack them on top of each other to save space (see photo below). Others prefer glass containers (e.g., clean recycled spaghetti sauce jars). Whatever you use, be sure to clean it thoroughly before using.

 

Round plastic container with trails of microworms crawling up the sides (Photo courtesy of Paul Leong)

Covered plastic containers like these can be stacked to save space. (Photo courtesy of Paul Leong)

Media

You have a choice of several different types of media for your worms to grow in. Here are a few:

• Mix up a batch of regular, unsalted oatmeal with water according to the directions on the box. You can make it a little thicker by adding a little more cereal and cooking it 15 extra seconds in the microwave. Let it cool to room temperature, and then put a half inch of the mixture on the bottom of your worm container. When the batch is at room temperature, add a couple pinches of Fleischmann's active yeast on the top.
• Alternatively, sprinkle about a half inch of uncooked Quaker Oats into the bottom of your worm container. Mix some warm (not hot) water into the oats until you have a mushy, slightly watery mix. You don't want standing water on top of the mix or the worms will drown. Sprinkle about 1/8 tsp. of baker's yeast on top of the mix. It's not necessary to measure it, just wing it.
• You can also use 3-4 teaspoonfuls of baby cereal (Gerber Rice or Rice with Apples & Bananas) mixed with fat free milk to a thick, pasty consistency. Add a dash of brewer's yeast if you wish. Some hobbyists find this mixture to be less pungent than using oatmeal or cornmeal media.

Whichever mixture you use, once the media has been prepared and cooled to room temperature, you can spoon a little of your starter culture in on top of it. The microworms live on top of the oatmeal mixture, so it's not necessary to have a very deep layer of media. Do not mix the culture into the media as this will very likely kill your culture.

Mix a new batch of media every week or so and add a small amount of it to your existing culture to it to keep your supply going. Be aware that if you let this mix sit for extended periods, the oatmeal will go bad and begin to smell. I mean really smell! The moral here is: once you have your new culture going, throw the old one out!

If you're not sure your worms are alive, hold the container up to light so that you can see a good reflection off the top. If it is glistening, then you have millions of tiny nematodes wriggling around on top and your culture is doing fine.

Temperature

The culture should be kept in a well lighted area at room temperature, 68-85°F.
Microworms can withstand temperatures below 32°F but greater daily production can be expected at higher temperatures; however, cultures last longer at lower temperatures.

Harvesting

After 3-7 days, you will see the microworms crawling up the sides of the container. Eventually they will reach the top. You can scrape them off the sides with a plastic spoon, cotton Q-tip, plastic scraper, wooden match stick, toothpick, or similar device. Even a finger will work

Swish the worms around in a container containing a small quantity of water. Using an eyedropper or pipette, suck up the amount you need for each fry tank. If you don't use all of the worms you harvested, throw the rest out. Don't try to put them back into your worm container, you'll just drown the other worms with too much water.

Another method:

Wait until the microworm worms have multiplied to such large numbers that the worms start to crawl up onto the container lid. At that point, all you have to do is take the lid off and lay it on the surface water of your fry aquarium. This method of harvesting is relatively clean -- there are usually very few traces of the culture medium mixed in with the worms that get to the lid. It is also more efficient because you can feed the worms directly without going through additional rinsing/cleaning and filtering steps.

 

Microworms have collected on the top of this container (Photo courtesy of Paul Leong).

A culture will usually last 2-3 weeks, depending on the ambient temperature of the room and other factors. To extend the life of the culture, you can add fresh culture media to the existing culture when the culture starts to become very "liquidy". The culture will eventually decline, as evidenced by a drop in the number of microworms you are able to harvest. The medium will have a thin, soupy consistency and the microworms will appear lethargic (less wiggling when viewed from above). If simply adding fresh media to the existing culture does not increase the microworm production, that is your cue to start a new batch.

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