Grindal Worms Culture on Polyester Foam

Michael Langerman
15 min readJan 25, 2022


Buy Grindal worms locally through Craigslist:

Or buy Grindal worms on Amazon (paid link):

I’ve been experimenting with culturing Grindal worms on different mediums since March 2021.

That’s when I got my first Grindal culture on soil.

I want to check Grindal worms this time on a less messy medium — polyester foam.

First, let’s prepare a plastic container with a cover.

Make needle sized holes in the cover for air circulation.

Here I have two pieces of polyester foam cut to fit inside of the container.

Any sponge like polyester foam would do for our purpose.

Pour some water on the foam to moisten it.

I use two layers of foam in this example, making it about 2 cm thick in total.

Grindal worms like moisture a lot, but they drown in water.

So, make sure to remove any excess water from the bottom of the container.

The container is ready and the foam is moist.

Also, I cut a piece of plastic to cover the foam.

Bend corners of the plastic piece to make it easier to pick it up from the container.

The piece of plastic helps to collect Grindal worms and also it reduces water evaporation.

There are different ways to seed a new culture of Grindal worms.

In this example, I move the plastic piece from the old well established Grindal worms culture to the new container.

Sprinkle a crushed flake of cereal on each layer of the foam for worms to feed on.

And spray some water to keep it all moist.

Put the piece of plastic on top.

The same goes for the old culture.

The new Grindal worms culture is set and ready on June 18th.

Check on Grindal worms cultures daily to keep them moisten and feed them only if necessary.

Let’s set up another Grindal worms culture.

I already prepared the container and made holes in the cover.

Here I use a different type of polyester foam for the base.

Any type of polyester foam would do.

I prefer to moisten the foam with aged algae rich water.

Remove excess water from the container.

This time, I seed the new culture with Grindal worms collected previously in water.

Here you can see Grindal worms wriggle on the bottom of the cups.

Grindal worms sink in the water, making it easier to separate them from Springtails in particular.

Pour water with Grindal worms on the foam.

Grindal worms start spreading around and burrow into the foam rather quickly.

Crush a flake of cereal on top.

Put a plastic piece on the top and cover the container.

All set and ready.

Check on Grindal worms cultures every day!

It takes 4–6 weeks for the population of Grindal worms culture to grow noticeably.

That is when I start collecting Grindal worms either to feed fish or to set up new cultures.

In this example, I wash Grindal worms off the plastic piece.

It is the cleanest way to collect Grindal worms.

I keep more than 4 Grindal worms cultures of different ages for continuous fish food supply.

Collect Grindal worms from mature cultures about once a week.

Feed Grindal worms once a day with a flake or two of cereal.

The more worms, the more food they consume, the more food you need to provide.

And keep all cultures moist.

Otherwise, Grindal worms get dehydrated and die very quickly!

From a well established Grindal worms culture, I collect enough worms to set up a new culture each week.

So, by end of the month I have 4 cultures.

Use collected Grindal worms to seed new cultures or to feed your pet fish, amphibians and such.

I feed my Endlers and Guppies different food 3 times a week.

One feeding of homemade fish food flakes, one feeding of Springtails and one feeding of Grindal worms.

I freeze Grindal worms collected on the days when I do not feed my fish.

Live wriggling Grindal worms certainly are much more attractive food for fish.

Frozen worms have the same nutritional value as live worms — my fish enjoy it.

Freezing worms is a way to preserve harvest for the days your fish need it.

July 21st

I show in this video only key points of care, skipping daily checks I do on every culture.

Checking on every culture daily is very important — keep that in mind!

Here I collect Grindal worms from the cover and from the piece of plastic from my oldest culture.

This culture has been productive since the middle of Spring.

It is the first culture I used polyester foam on top of soil shown in my previous video.

Feed, moisten, and cover the container — that is a daily chore.

Feed less or skip feeding if food is left from previous feeding.

And skip moistening and remove excess water if there is any as in this example.

Grindal worms like to bathe in drops of water for hours.

However, they will drown if there is too much water for them to climb out to surface.

Also, excess water comes with dissolved waste produced by Grindal worms.

Reducing the waste helps to keep the colony healthy.

September 27th.

In this example, I wash Grindal worms from the cover and both sides of the plastic piece.

Yes, Grindal worms climb on both sides of the plastic piece.

Left on the dry surface, worms dehydrate and die quick.

When there are so many worms as you see here, I just scoop them with my finger or with a soft brush.

Grindal worms thrive in wet environments suitable for Springtails.

It is just a matter of time before Springtails intrude in your Grindal worms cultures.

Here you can see Springtails on the bottom of the container.

Springtails are actually a very welcome addition to my Grindal worms cultures for a number of reasons.

Live Springtails stay on the water’s surface while Grindal worms sink to the bottom.

It makes it easy to separate Springtails from Grindal worms as we collect worms from the bottom.

OK, let me just finish feeding this culture and I will show it to you.

I intend to publish more than a couple videos about Springtails.

That is where you will get all the details.

In the mean time, if you get Springtails in your Grindal culture — don’t panic.

Springtails are harmless and beneficial to Grindal worms cultures.

Top feeding fish feed on Springtails too!

I use a pipette to pick Grindal worms from the bottom.

And Springtails stay on the water’s surface.

You can use them to start Springtails culture.

Or just empty the container into your aquarium for fish to eat them.

And there is another way to start a new Grindal worm culture from an old culture.

November 12th.

Here you can see about 4 month old culture of Grindal worms I set up at the beginning of this video.

Back then, I put two layers of polyester foam.

So now, I can just move one layer of the polyester foam into a new container.

And the rest goes in the same way.

Feed, moisten, and cover the container daily.

Each polyester layer has actively breeding Grindal worms.

It means that I just made two well established cultures.

By far it is the most efficient way of setting up new cultures.

Culturing Grindal worms on a synthetic medium seems to be the cleanest of all the other mediums I tried so far.

The polyester foam can be reused if you have to reset the culture.

Which may happened if an old culture gets exhausted or die out for whatever reasons.

I lost one culture out of my first three dozens and successfully re-set it in this way.

There is nothing permanent in this world so…be prepared.

And the simplest way to prepare is to set up a spare culture when you can.

An established culture of this size yields more Grindal worms a week than half a dozen adult Endlers can eat in one feeding.

In this example, I harvest Grindal worms from a plastic piece enough for 3 feedings.

My highest harvest yet for that matter was 6 feedings from this culture which is equal to 6 new setups.

Feeding your pets with the best food is the whole point of culturing Grindal worms.

Seeing your pets go in frenzy after Grindal worms speaks for itself.

There is much more to say about Grindal worms, and feeding fish and etc.

I have a couple more videos coming on this subject.

Though, you already reap the gifts of culturing Grindal worms.

And should be ready to treat your pets to Grindal worms, one of the best live fish foods everyone can grow at home.

Have fun and happy pets :)