A guide to culturing Grindal Worms




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Grindal worms are small white relatives of earthworms. They are small, healthy, and best of all, live food that appeal to a wide variety of aquatic fish like Angelfish or invertebrates like Red Cherry Shrimp. They are also a more nutritious option versus something like frozen bloodworms.

Now there are a few methods on how to culture grindal worms as well as tricks and techniques from hobbyists that work for them. I will go over the most common method and standard principles to get you started in culturing your own free live food for your Fauna!

This grindal worm culturing guide is a guest post by Jesse from Aquatic Mag!


There are a few things you will need to get a culture setup. Typically you can find most of this stuff around the house or at your local store. You will also need to buy or find someone with a start culture of grindal worms; local fish stores or fish clubs should usually be able to help you with this.

  • Empty food container with a tight fitting lid
  • Sponge filter or small aquarium filter pad
  • Plastic or glass sheet that fits inside the food container
  • Coconut fiber (soak before using)
  • Spray bottle with reverse osmosis/deionized water
  • Dry kitten food or high quality dry dog food
  • Starter culture of grindal worms
  • Jar or glass (for later)

Building the Grindal Worms Culture

Making the lid – make 4 or more holes for air ventilation for your grindal worms. Once the holes have been made plug them with the aquarium filtration pad or sponge filter to keep any flies or insects from entering into the culture.

Making the container – add one to two ounces of coconut fiber to the bottom. It should be damp to the touch but not soaked. A good indicator is to squeeze the coconut fiber: it should form a ball and release a small amount of water.

Add your starter grindal worms and a small amount of food to the top of the substrate. Then mist the substrate and food with your spray bottle making sure to get the top layer damp enough. Carefully lay the plastic or glass sheet on top of the starter grindal worms culture and food. This will help you later in maintenance and harvesting. Lastly, just add the tight fitting lid to the container and you’re done building the grindal worm culture!

Store your grindal colony container in a dark, warm place as grindal worms prefer temperatures around 72-78 °F/22-25.5 °C  for better breeding rates. Be sure to keep the air holes cleared for ventilation as well.


Every 24 hours, lift up the plastic or glass sheet and add more food to the culture. Once again, spray it with the water bottle and then replace the plastic or glass sheet as well as closing the lid. Feed less or more depending on whether the grindal worms consume all the food within these 24 hours.

Every few months, it is essential to replace half of the substrate with fresh coconut fiber. This is to prevent a culture crash. The old substrate may be used to start another culture or used for compost in a garden.

I recommend starting another grindal worm culture and at least keeping 3 cultures running at a time and in different stages so if one culture crashes, you have the others to recover from.


When harvesting the grindal worms, the best method I found was to use the plastic or glass sheet to lift them up: it typically will have a load of grindal worms attached to it. Use a cotton swab or your finger to extract the worms and then place them in a jar or glass full of water. Swoosh or stir the water – the grindal worms will quickly sink to the bottom. Pour out some of the water to remove the excess coconut fiber and food from jar. This process can take a bit of time and practice.

Once you feel most of the debris is removed, let the grindal worms sit and use an eye dropper to suck them up in clumps then feed them to your fish.

Food for Thought

  • One good thing about grindal worm cultures is that they don’t smell foul like some other live cultures. If they do start to have a smell to them then it’s an indicator of a possible crash of that colony.
  • Grindal worms like the dark so try to keep the enclosure blacked out or in a dark location. While harvesting, be quick about it because light will make them want to dig back into the substrate and less can be harvested.
  • Mites can be a pest if they outcompete your grindal worms for food. They are typically quicker and have a better sense of finding surrounding food than the grindal worms. If this is the case, add more food to the container then in about an hour remove any food that has mites attached to it.
  • If you want to start up a new culture but have mites in the old one, you can harvest the grindal worms into a glass jar of water then swirl them around while pouring out the excess floating debris. This will remove most of the mites. You can do this until you start to see your grindal worms straighten out and stiffen up, meaning they are low on o2.

If you still have questions about culturing your own live grindal worms or want to share your own experiences with this great live food, don’t hesitate to leave a comment below. Happy fishkeeping!

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12 thoughts on “A guide to culturing Grindal Worms”

    • Hi Kasim!
      It is hard to say without seeing a picture. Are you saying that there is another worm inside of your grindal worm? This could be a parasite but I would need some more info.

  1. eBay usually have a few adverts for grindal worms. Read the reviews before ordering because
    sometimes, but not often , you’ll get a load of compost and very few worms. Usually the vendors
    are keen aquarists who generally just ask a modest sum of about 2 to £3 and will resend the order
    if by chance your grindals fail to survive the journey.. If all else fails you can always ask for a refund.

  2. I have a paludarium will red devil crabs. Can I put these in the land portion (lots of plants and mosses with springtails and isopods) and let them grow?

    • You know, that’s a good point. I think you might be able to sustain somewhat of a population this way as long as you keep things dark in the area the worms are in, but I’d be worried the crabs would go to town on them. They can’t exactly get away as easily as something like a springtail. If you try, let me know!

  3. How long can grindal worms go without being fed? I am worried about my cultures since we will be out for a week this Summer.

    • I’ve never tried leaving a grindalworm colony for so long, but I’m thinking it might work if you find some type of slow release food. Might be a totally dumb idea, but maybe the weekend blocks that they sell for aquariums?

      I hope it works out!

      • Just a word about grind all worms. Have been struggling for some weeks to get some response from my very lethargic grindal worms. Read and reread articles but no progress. Then I came across the article in this program which mentioned the importance of maintaining a fairly high temperature 78 degrees F . I got out an old seed propagater and
        placed a container of grindal worms in there as an experiment. What a difference in just 24 hours. The surface of the culture was teeming with active grindal worms. Thank you, thank you…problem solved . Must now learn how to adjust and avoid too much heat.

    • Hi! They’re a little difficult to find aren’t they? I think you can buy them online at some stores that sell fish foods, reptile supplies etc., that sort of thing. Not sure how you’d find them in nature 🙂


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