Grindal worms (Panagrellus species) are one of the “old standby” live foods that can be easily cultured in the amateur fishroom. They are fairly small, thus suitable for many of the smaller fish such as dwarf cichlids, killifish, and fry.
Unlike whiteworms, which prefer cooler temperatures, grindal worms do best at about 70°F. Overall, they are fairly easy to culture.
“The best way to get grindals going,” according to Richard Levenberg, “is to put about 3/4″ of potting soil in a plastic shoebox. Thoroughly wet with aged water, but don’t let get soupy.” Dump in the worms. With the back of a spoon make depressions in the soil and in each place a small amount (1/8 tsp.) of Gerber’s baby cereal (he uses rice). Place the covered container in a dim or dark location at room temperature. Feed the culture when the food is gone; when the soil dries out, add more water.
Stuart Raymond uses a slightly different approach. “Get some peat and put it in a small (margarine size) container, to about 2 cms deep. Make up a thick paste of oats and water, enough to cover about half the surface of the peat.” Dump in the grindal worms. After a couple of weeks, make up a new culture, since the first one will have lots of mites in it.Feeding Grindals
“I raise lots of grindal worms to feed my killies, usually with 12-20 plastic shoe box cultures going at once,” says Bruce Turner. “I harvest two or three times a week.” He feeds Gerber’s baby cereal fortified with vitamin C.
Most agree that the usual food is baby food cereal, but other foods have also been used successfully. Properly crumbled, old flake fish food works well, as do crumbled trout, dog, or cat chow. “I use Purina Meow Mix, but any cat food with 30% protein will be fine,” says George Slusarczuk. “I feed the ground pellets mixed with regular oatmeal.”
The worms tend to come to the surface when there is food, but disappear once the food runs out (which can take less than 12 hours once the culture is going well). This means that you may have to time feedings to have the worms when you want them.
To harvest grindals, put a piece of glass on top of the soil, wait about 20 minutes, and remove. You can wash the worms off the glass with water and siphon them out to feed, or you can simply wipe them off the glass with a small brush, a popsicle stick, or your finger.An Alternate Culture Medium
A number of aquarists have found that grindal worms can be effectively cultured on foam. Thoroughly soak a piece of open call foam cut just slightly smaller than a standard plastic shoebox. Between 1/4-1/2″ of standing water should remain in the box. This should be changed occasionally, so it remains fresh. The worms live in the open cells of the foam at the optimum moisture level; they feed on the surface and are harvested in the usual way.
Barry Cooper has cultured grindals on egg-crate foam (smooth on one side and bumpy on the other). The foam culture “is far better than the soil type if you can get it going properly,” says Barry. He feeds baby cereal into which he mixes finely powdered flake food. “You can see blooms of tiny worms on the grindal cultures,” he says. “In a day or two you’ll get lots of larger worms.”
Mike Florez reports that he has cultured grindals in foam using 3-4 layers of 1/2″ foam stacked atop one another, with food placed between the layers. The worms “appear on all the layers and can be harvested without disturbing the layer with food.”
“I’ve been culturing grindals on [the same] foam for over four years,” reports Karl Johnson. “I’ve been able to successfully keep the mite populations at zero, except when the culture cases were cracked or broken,” usually due to plastic failure.
The most common pest in grindal cultures seem to be mites. Aquarists deal with them in a number of ways: many simply start new cultures every so often and throw away the old ones. Other treatments include lightly scorching the surface using a propane torch (the worms retreat to the moister depths, the mites succumb), or sprinkling used coffee grounds on the surface.
“All of my grindal cultures serve double-duty for both grindals and African red wiggler earthworms,” says Stephen Shine. “The redworms seem to keep the medium churned up a bit, which seems to upset mites. And the worms love the coffee grounds.”
– G.C.K.A. Newsletter, July 1999