The key to successfully breeding and raising any species of fish is to have the proper food available at the proper time. I am sure that many of you have struggled to get brine shrimp nauplii to hatch in time to feed newly hatched fry. It is frustrating to see the new babies starve because the brine culture didn’t work or because the newly hatched fry wouldn’t accept the shrimp (many species are too small at birth to take shrimp). What is needed is an alternative live food.
I believe that microworms are the perfect first food for fry, and they complement brine shrimp nauplii in a feeding program. They are easily cultured and can be available on a continuous basis to feed those unexpected batches of fry.
Microworms are small colorless nematodes, approximately 1 millimeter long. They can be cultured easily by the home aquarist. Microworms are not sensitive to their environment and will thrive at most room temperatures. They are easy to feed to your fish and are readily accepted by fry and most small fish. However, these worms are too small to interest the larger varieties of fish kept in home aquariums.
As soon as your microworm culture has been activated, the only attention it requires is periodic sub-culturing. This is done to avoid any offensive odors caused by the culture medium going sour. It also prevents the culture from drying out. A single culture can be sub-cultured into as many cultures as you may need to meet present and future feeding requirements.
Microworm cultures can be obtained from pet stores, through mail order sources (listed in the classified section of most hobby magazines) or from other hobbyists. They are even available in a dry, vitamin-enriched form (just add water) sold under the trade name of Nemos.
Once your starter culture is received, you should transfer it to two or three containers in which you intend to grow the worms. Starting more than one culture ensures a back-up if one should crash. The containers can be any small refrigerator dish, freezer container, glass jar or the like. I use square, half-pint-size freezer containers — their translucent quality enables me to see the worms making their way up the sides. The container should have a secure-fitting lid with six to eight ¼-inch holes drilled in it. If the culture container is airtight the worms will perish from lack of oxygen.
The next step is to prepare a culture medium. The medium can be most any kind of prepared cereal, including oatmeal, baby food or even yellow cornmeal.
The medium is prepared by mixing in enough tepid water to create a paste that is somewhere between the consistency of a thin milkshake and the cereal as it would be prepared for breakfast. Place this in the container to a depth of ¼ to ½ inch. Next, add a tweezer-sized pinch of baker’s or brewer’s yeast to the top of the medium, and then add your starter culture.
At temperatures between 60 and 80 degrees Fahrenheit, your culture should be ready to use within three to five days. It is easy to see the tiny worms making their way up the sides of the container. When held under a light, the surface of the culture will appear to be shimmering — this is the movement of millions of microworms on its surface.
To feed your fish, scrape the worms from the sides of the container using a wooden stick, a plastic knife, your finger or any other object that works for you. Then rinse the worms into a glass of water and dispense with an eye dropper or baster.
The theory behind this form of culture medium is that the microworms feed off of the yeast, which in turn makes a meal from the cereal. As the culture starts to age it will become thinner. If it starts giving off a sour smell it is time to start another.
To avoid any smelly problems, it is wise to sub-culture every two to three weeks. To do this, simply prepare a new mix of medium and add yeast and a small portion of your existing microworms. Now you’re ready to begin again.
You’ll find microworms are a fine substitute for freshly hatched brine shrimp in feeding new fry. They are always available, readily accepted, easily cultured and inexpensive. Once you have invested in the initial culture, you can maintain an infinite supply of microworms if you sub-culture regularly. In the three years that I have been culturing them I have never had a culture fail.
So, go ahead and give microworm culturing a try. They are inexpensive, readily available and easy to raise — and your new fry and small fish will love them.