Grindal worms refer to small, white non-parasitic worms often employed by hobbyists in feeding varieties of fish, amphibians, and invertebrates. These worms are very hardy and can be cultured even by beginners.
This article provides valuable insight into the culture of Grindal worms for the purpose of feeding aquarium fauna.
What are Grindal Worms?
Grindal worms (Enchytraeus buchholzi) are enchrytaeid oligochaete worms, and they are smaller relatives of White worms (Enchytraeus albidus) which are equally cultured as aquarium fish food.
Interesting fact: This species was named after Mrs. Morten Grindal of Sweden, and she discovered these worms while improving on a White worm culture.
They have a white, cream color and grow up to ½ inch (up to 1.5 cm) in length and up to 0.015 inches (0.4 mm) in diameter.
They can live up to 30 days.
Grindal worms are hermaphroditic i.e. possessing both male and female reproductive organs, and they are capable of producing a mass of cocoons (each containing about 9-25 eggs).
Grindal worms are extremely prolific. Under optimal conditions, they can easily double their biomass in 3-4 days!
Grindal Worms as Live Food
Grindal worms contain high protein (70%), minimal fat (14%), and carbohydrates (10%) with a large amount of vitamin A and carotene, making it a healthy and nutritious food option for your fish and other tank inhabitants.
Also, since many fish and inverts require live foods as well as a mixed/varied diet; feeding your tank critters with these worms will help keep them active, healthy, and well-nourished.
Supplies for Culturing Grindal Worms
The following supplies are needed to culture Grindal worms.
- Starter culture of Grindal worms.
- Culture vessel: Plastic food container with a tight-fitting lid.
- Bedding: Coconut fibre.
- Protection: Women’s nylon stockings or aquarium filter floss.
- Harvesting: Plastic or glass sheet
- Maintenance: Spray bottle with dechlorinated water.
- Optional: Jar, cotton swabs, turkey baster, or pipette.
Basic Set Up for Grindal Worms Culture
- Here, you need to make a few small holes in the lid for ventilation. Drill or pierce the lid with something sharp.
- Afterward, you need to cover the holes to prevent any pests (mites, ants, and flies) from making their way into the culture vessel.
For example, in my experience, the easier and safer way is to use women’s nylon stockings. Put it on the plastic container and press it with the lid.
Another way is to cut little pieces of aquarium filter floss and fit them in the holes. However, be very careful with that, it can be good against pests but bad for ventilation.
- Typical substrates for culturing Grindal worms include coconut fibre, potting soil, and peat moss.
- However, coconut fibre appears to be the most preferred choice. Coconut fibre usually comes in dried compact bricks, so you are required to soften the brick to make it ready for use.
- Simply place the dried brick in a small container, add 2 liters (about 4-5 gallons) of fresh water and leave it until it is entirely softened. Within this period, the brick will gradually soften and expand as it soaks up water from the container.
- Keep in mind that the substrate should be damp, if soggy, then you need to squeeze out excess water from the coconut fibre. The substrate is deemed fit for use if it forms a ball and releases small drops of water when squeezed.
- Going further, add about 1-2 inches (3-5 cm) of damp coconut fibre to the bottom of the culture container and level it. There is no need for the deep substrate to culture Grindal worms.
Note: Use gloves. It can be really dirty.
- Once done, add the starter culture to the center of the substrate and feed the worms their first meal.
- Proceed to mist the bedding and dry food adequately with dechlorinated water from your spray bottle.
- Now, you can lay the plastic or glass sheet on the substrate. The sheet will come in handy during the harvesting process.
- Grindal worms thrive at room temperature, so do not bother to employ any heating agent.
Note: They also stop reproducing if the temperature drops below 14 °C (57 °F).
At this juncture, you are almost done with setting up the Grindal worm culture. Finish off by adding the tight-fitting lid to the culture container and storing it away in a dark, warm room.
- Optimal temperature: 20 – 25 °С (68 – 77 °F)
- Humidity of the substrate: 23 – 25%,
- pH of the substrate: 6.2 – 6.7
Feeding Grindal Worms
If you fancy a healthy worm colony/increased yield within a short period, then you should understand how vital it is to feed the Grindal worms every single day. Ensure to supply nutritious food to your worms, and while doing so, stay clear of foods that can introduce pests to the culture.
You can feed your Grindal worms with almost anything, but the best results will be with:
- dry dog food,
- dry kitten food,
- fish flakes/pellets,
- white bread with milk,
- chopped leafy vegetables,
- oat flour.
It is recommended to vary the diet from time to time. Also, if you use dog/cat/fish food – do not forget to crush it for a better result.
Do not bury the food into the substrate. Put the food on top of the substrate, push it down a little bit, sprinkle it with water, and cover it with glass. It will help you with harvesting them later.
How often to feed Grindal Worms
According to some studies, Grindal worms were fed once per 2-3 days for mass production.
At the same time, for common people, it would be easier to control feeding if they do it every day. So, each day i.e. after a 24-hour window, raise the plastic/glass sheet and place new food for your Grindal worms.
Endeavor to mist the food mildly since Grindal worms prefer their food moist.
How much to feed Grindal Worms
There is no definite quantity of food to feed the worm colony during the course of their lives, the reason being that their feeding pattern tend to change as they grow.
Hence, you need to increase the quantity of the food as the worms grow, making sure that they get enough to eat for sustenance. Nonetheless, if you notice too much leftovers during the next feeding time, then you should cut back on food portions.
The optimal dose is usually determined empirically. Too much leftovers are a sign of overfeeding.
Maintenance of Grindal Worms
They prefer dark environments with standard room temperatures to thrive.
Be sure to keep the little air vents tidy, you may as well change the pieces of filter floss after some time in case of dust accumulation.
Similarly, swapping out the existing bedding with fresh coconut fibre after 3-4 months is crucial to prevent culture crash, or to eradicate mites or mold.
Always mist the bedding from time to time as low soil moisture can hinder the reproduction and growth of the Grindal worms.
Harvesting Grindal Worms
Grindal worms grow and reproduce very quickly, thus you should have plenty of worms to harvest after few weeks of starting the culture. In a well-establish setup, it is possible to collect them 2-3 times a day!
- To harvest your Grindal worms just take out the plastic or glass sheet; worms tend to stick to the sheet as it is very close to the food.
Tip: you can use even a CD disk cover. Another option is to use
- Next, use a cotton swab to dislodge the worms from the underside of the glass/plastic sheet into a jar of clean water.
- Allow some time for the Grindal worms to settle at the bottom of the jar, swirl the jar and pour off the water to remove remnants of coconut fibre and/or food. Do this repeatedly until most of the debris is gone, leaving only the worms.
The Grindal worms are now ready to be fed to your aquarium pets. Simply collect the worms using a turkey baster or pipette and squirt them into the fish tank.
Tip: Grindal worms can be easily stored in the freezer for 3-4 months.
Note: Grindal worms contain high protein (70%), therefore, do not give this food to your pets all the time.
|It is important to make sure that most Grindal worms are eaten in the tank.
The point is that these worms cannot survive in the water for more than a few hours. If not eaten, they will bury into the substrate and die there. As a result, they will decompose in the substrate and release ammonia later.
Problems Associated with Grindal Worms
Pests at setting up: There are chances of encountering pests in the starter culture, food, and even the substrates (peat moss and potting soil).
Solution: Hence why it is advised to boil/rinse peat moss. And on the other hand, to heat/microwave potting soil to sterilize it and mitigate the risk of contamination. Some aquarium enthusiasts equally microwave coconut fibre and allow it to cool before usage.
Pests during culturing: In some cases, you can discover pests (mites or flies) in your bedding during the culturing process. If so, you need to take prompt action because these pests can suppress the culturing process.
Solution: Collect and transfer the worms into a container of water, swirl it gently and pour off the water to remove the pests. Afterward, start a new culture with fresh coconut fibre and keep it going!
Smell: In addition, the presence of an unpleasant smell often points to a culture crash.
Solution: Generally, there is nothing you can do. So split the colony and start a new culture with fresh bedding.
Ventilation problems: The worm cultures can crash when the airholes get clogged.
Solution: Check them periodically and remove any dirt.
Final thoughts: Avoid pest-contaminated foods, cover the culture container with a tight-fitting lid, and ALWAYS use some form of protection (nylon stockings or aquarium filter floss) to discourage entry of pests.
Grindal worms are relatively easy to culture, they require little attention, and the cost of setup is quite inexpensive.
Compared to most aquarium live food options, it takes minimal effort and resources to establish and maintain a Grindal worm culture. And this species doesn’t need a large enclosure or special requirements like salinity, lighting, supplemental aeration, and heating to thrive.
Grindal worms is an excellent food source for many species of fish, crabs, and crayfish irrespective of their size. You can serve these little worms to fry, juvenile, and adult fish, as well as amphibians e.g. newts, salamanders, and inverts such as crayfish, shrimp, lobsters, and crabs.