Homegrown Food - The Greatness of Grindal Worms

Grindal (pronounced grin-doll) worms, or Enchytraeus buchholzi are a popular live fish food, especially for small picky fish, or baby fish. They are often used when baby fish are too big to eat vinegar or microworms, but maybe not ready for tubifex and brine. These worms are small at around ¼ inch long and as thin as a thread at .002 inches in diameter. This means just about anything can eat them, and pretty much everything will. They are also very nutritious; they are roughly 70% protein, 15% fat, 10% carbohydrate and 5% mineral.

The Grindal worm got its name from a Mrs. Morton Grindal, when she first isolated them from a white worm culture in the 1950s (in Sweden). White worm culturing is another Homegrown Fish Food article. Grindal worms are extraordinarily prolific, every worm capable of producing over 1000 offspring over the course of its life. These worms are hermaphroditic (having male and female reproductive bits) and capable of reproducing completely on their own. Their ease of culture, attractiveness as food, and excellent nutritional profile makes them ideal candidates for home rearing.

Luckily, this very nutritious food is quite easy to culture; they can be raised in just about anything. Most importantly, whatever you choose for a container must allow for air movement, without letting flies or other invaders contaminate the culture. Some people use small wooden boxes, like cigar boxes, others use plastic take-out containers with holes cut in them. You'll need to make sure that the holes in the containers are so small that flies can't get in, or that they are covered with something like cotton balls or other impassible material that allows good air flow. Smaller containers will allow for easier extraction of more worms, and you won't need a huge amount of space to generate lots of worms, so we suggest keeping it small.

In the bottom of this container, you need a small amount of some neutral pH media, you should only need an inch or two of depth. It should hold moisture well. We've seen people use coconut husks, and this is a pretty good choice, it can also be mixed with a small amount of potting soil, and is generally an acceptable pH, in the high 6s. You could also mix potting soil with sphagnum or peat moss, and this combination is the perfect consistency, but has a tendency to be very low pH because of the moss, and so adjustments may need to be made. Other people successfully use polyscrubber pads and sponges; these have the benefit of being pH neutral, but seem to dry out quickly, so may require a little more attention to maintain a proper moisture level. It's important to replace ½ of this substrate every few months. It will help prevent colony collapse and you can use the old half of the substrate to create a new culture.

Whatever you choose for substrate, you'll need to maintain a moist but not wet environment. Make sure you are using water that had no chlorine in it as worms are very sensitive to it. A good way to maintain this moisture level is with a sprayer or mister and add a spritz every day when you feed. If you notice the worms burrowing into the substrate, they are looking for moisture and your culture is too dry. If the culture starts to stink, this is a sign it's too wet and there isn't enough oxygen. This is usually a very odor-free process. If it smells, there is a good chance the culture is going to crash. For those of you with a way to measure soil moisture, 20% is about optimum.

Next up is you'll need to purchase a clean worm culture. These are sometimes available from your Local Fish Store and are frequently available online as well. It's better to be able to source them locally, as you get to make sure the culture smells good and looks clean. If this isn't possible for you, there are many cultures available on sites like E-Bay, just make sure you pay for overnight shipping, as they need food, oxygen and moisture, all three of which can be in short supply if shipping takes too long. When searching online for cultures to buy, some sellers will spell the word incorrectly as “Grindle.” This may help you find a source that is closer to home.

Once you have your container and moisture level worked out, and have a healthy worm culture, you need to add food. You can feed this a huge variety of things. Things like flake or pellet fish food, high quality dry dog / cat food, cooked oats, bread, mashed starchy vegetables like potatoes and carrots, even mashed bananas. You'll want to feed them every day, but how much is going to depend on the size of your culture. Start with a very small amount of food, maybe a teaspoon worth. Check back in on the culture in 24 hours. If the food is completely gone, feed a bit more, perhaps two teaspoons. If the food is not gone, remove the uneaten food (while trying to leave as many worms as possible behind) and make an adjustment downward equal to the amount of food left over. This sounds harder than it is, and once you have been feeding for a couple days, you'll have the hang of it. As the culture grows, you'll obviously need to add more food daily.

Harvesting worms for feeding is really quite easy. Just cut a piece of plastic (with airholes) or screening to fit over but touching the food. Worms will climb onto this, and you can remove it and rinse off the live worms into your aquarium. You can also use this mechanism to harvest worms for starting new cultures. Keep in mind that the worms will move away from the light, so if the container is left in total darkness, the worms will stay high in the culture looking for food. If you leave it in the light, they will burrow and be harder to find, harder to harvest, and not reproduce as quickly.

We think you'll find that growing your own Grindal worms is pretty straightforward, and you'll be shocked at how quickly they grow. The most common issue you might right into is mites. If mites get into the culture, they can out compete the worms for food and your culture will grow slowly, if at all. You can try to remove the mites by over feeding the culture, leaving it in the light and waiting a couple hours and removing all the food. The mites move much more quickly than the worms, are not as reactive to light and will be the first to the food. By removing the food, you'll also be removing most of the mites. Repeat this a couple times and you may be able to save the culture.

We suggest keeping at least two cultures and three would be better. It is not much more work to maintain a couple extras, and if you have a problem with mites (or anything else) in one of the cultures, you can just toss it in the garden, and use one of the healthy cultures to start a new, mite free, wormy farm. Just pull out some substrate, make sure it's got some worms in it, and then repeat the above process. It's the best and easiest way to fix issues that arise. If your culture starts to smell (as referenced earlier), it's time to remove a small bit of it and start a new culture or toss it and start anew from one of your extra cultures.

Basically, your worms will thrive if you give them a dark home, enough food, a good moisture level, a pH between 6.7 and 7.3 and a temperature in the mid to high 70's Fahrenheit. While the worms will grow in conditions outside this range, they will generally do so much more slowly, and if the conditions get too far outside this range, the colony runs the risk of collapse. This sounds like a complicated list, but it isn't really. Most of these things are easy to manage and if you choose a good substrate, the pH will take care of itself. If you're looking for an amazing, nutritious food for your smaller, pickier fish, or some baby fish not big enough for processed foods yet, Grindal worms are an easy to culture choice for you to try! Head over to your LFS and ask them if they have a culture you can buy!