How to Tell If Your Kombucha Has Vinegar Eels (and what to do about it)

What Are Vinegar Eels and Why Would They Be in My Kombucha?

Vinegar eels are small nematodes which, as their name suggests are most commonly found in raw or unpasteurized vinegars. They can withstand the acidic conditions, and live off of ingesting the microbes which implement the fermentation process.

Vinegar Eels are actually not ‘eels’ but worms (nematodes), despite the name.

Unfortunately they can also live in kombucha brews and feed off of the SCOBY microbes (bacteria and yeasts).

This makes quite a lot of sense, as fermented vinegars, such as apple cider vinegar and rice vinegar are quite similar to very mature kombucha. For more info on the similarities and differences between kombucha and naturally fermented vinegars, you can check out The Difference Between Kombucha and Vinegar.

Vinegar Eel F&Q

Before we talk about what to do if you get a vinegar eel infestation, here’s some pressing answer to the main questions you may have about these worms.

What Vinegar Eels Look Like

Vinegar eels are very small — they are at most about 1/16 of an inch in length. You can see them, but barely.

Here’s what they look like in the wild:

Here’s a close up look at them from a magnifying glass:

How Do Vinegar Eels Get Into Your Kombucha

You are probably wondering how vinegar eels could possibly find their way into a batch of kombucha. The answer is that since raw and natural vinegar can often contain vinegar eels, if you or the person who you got your SCOBY from, used raw/natural vinegar as starter liquid or to rinse out their brewing and storage vessels, then this is most probably the source of the creepy little buggers.

Ever wondered why most kombucha making instructions direct one to use spirit vinegar for cleaning purposes and as a starter liquid substitute? This is the reason!

Yes, this product, or a product like it may be responsible for your worm infestation:

The truth is that these worms infest a lot of vinegar products. Most commercial vinegar products do filter the worms out prior to processing or are prevented from growing via pasteurization. However, some do escape so it’s not unheard of to find them — living or dead — in many products that contain natural vinegar. Vinegar eels are even purposely grown by companies to feed baby fish in fish farms!

You can actually easily grow your own Vinegar eels in a couple weeks if you take some raw vinegar and leave it sitting around for a month (as explained by this Ripley’s Believe It Or Not article)

Are Vinegar Eels Dangerous?

The good news is that although the idea of them is extremely off-putting, vinegar eels, or Turbatrix aceti, have been deemed by FDA as harmless to humans and non parasitic. So if you have already ingested some, do not panic, they will simply pass through your system without doing any harm. You may even get a bit of extra protein from them!

However the bad news is that while vinegar eels may not be harmful to you and I, they are to the kombucha SCOBY. As they feed off of the microbes which make up the culture and cause fermentation, with time they will impact the health of your SCOBY severely.

If you are noticing the following problems with your SCOBY culture and fermentations, then it is a good idea to check for vinegar eels.

Your kombucha is not maturing as quickly as it usually does.

The culture lacks structure and is starting to deteriorate.

The flavor profile has undergone a change unexpectedly which is not linked to a difference in ingredients or conditions.

How Do I Know If I Have Vinegar Eels in My Kombucha?

While an infestation of vinegar eels can go unnoticed for many brews, it is not too difficult to spot them. Although they are not usually apparent at a soft glance while you are handling your kombucha, they can be seen with the naked eye.

How to Spot Vinegar Eels in Your Kombucha



The best way to ensure that you will see the vinegar eels if they are present, even in a small quantity or size, is to take your brew into a dark room or cupboard with a flashlight. If your brewing vessel is glass, then simply shine the beam of the flashlight through the side. If the brewing vessel is ceramic then shine the light into the top. If vinegar eels are present in your brew, then you should be able to see them wriggling towards the light.

Here’s a graphic showing you how to spot the eels in your kombucha:

How to Get Rid of Vinegar Eels

It’s very hard to get rid of vinegar eels — in fact, you just have to start over from scratch. Here’s what to if you have an infestation.

Step 1: Throw It All Away

If, when doing your flashlight inspection, it is revealed that you do have a vinegar eel infestation, then it means that you will have to do the Big Dump (i.e. throw the batch + SCOBY away). This means throwing out everything. The SCOBY, brewing tea, stored starter liquid and even extra SCOBYs stored in SCOBY hotels (if you want more info on SCOBY Hotels check out How to Create a Kombucha SCOBY Hotel).

Unless the extra SCOBYs where stored long ago, then it is most likely that they too will contain vinegar eels. If you want to check, you can do the flashlight test. If you do not see any vinegar eels in your SCOBY hotel, then you might be lucky enough to be able to use them to start your new vinegar-eel-free brews, however there is a good chance that the eels might still show up.

To be absolutely 100% certain that you will not experience another vinegar eel infestation, it is perhaps best to purchase a new SCOBY from a reputable source.

Step 2: Sterilize Your Vessels and Equipment

Once you have disposed of your SCOBY and tea (remember you can always put them into the compost or into your garden or pot plants, see What To Do With Extra SCOBYs) it is now time to sterilize your kombucha vessels and equipment. Vinegar eels are tenacious creatures, and you will have to fight them will boiling water and spirit vinegar.

Note here we say use SPIRIT VINEGAR and not Raw Vinegar. You wouldn’t want the whole cycle repeated by making the simple mistake of using raw vinegar as a sterilizer.

Here’s how to sterilize your equipment properly:

Assemble all of your brewing containers , second ferment containers (if you have yet to learn of second ferments take a look at this post How To Make Second Ferment Kombucha) ready-to-drink kombucha bottles and all other equipment and utensils, such as spoons, gloves, jugs and cups.

, second ferment containers (if you have yet to learn of second ferments take a look at this post How To Make Second Ferment Kombucha) ready-to-drink kombucha bottles and all other equipment and utensils, such as spoons, gloves, jugs and cups. Wash all of these with boiling water and rinse with spirit vinegar . Be careful of washing glass with boiling water, as the heat can cause it to crack. If all of your vessels are glass, you can reduce the temperature of the water very slightly in order to avoid cracking and shattering. But do not drop the temperature too much; otherwise the sterilization might not be effective.

. Be careful of washing glass with boiling water, as the heat can cause it to crack. If all of your vessels are glass, you can reduce the temperature of the water very slightly in order to avoid cracking and shattering. But do not drop the temperature too much; otherwise the sterilization might not be effective. Think hard about all the things that come into contact with your kombucha. There might be something that I missed in the list above which you will need to sterilize in order for your new batches of kombucha to remain vinegar eel free.

Step 3: Brew a New Batch of Kombucha from another non-contaminated source

If you have a backup SCOBY source that’s free of vinegar eels, you’ll use this as the source for new Kombucha. If not, you’ll need to buy a new SCOBY online or find someone to give you a new one. The key here is to use a NEW SCOBY source completely. You don’t want to have another infestation problem; the best way to prevent that here is to start with a fresh SCOBY that had not contact with the infestation.

The Final Word

Although the sight of dozens and dozens of small wriggly worms (!) squirming about in your lovely batch of home brewing kombucha can instill horror into even the most hardy of us home brewers – you can be confidant that any you might have accidentally ingested before discovering the infestation are probably not in your body any more. If there are any in your digestive tract, they would be from ingesting them within a window of about two days, and most likely they will be evacuated the next time you go to the toilet.

Even if you have been drinking batches of kombucha which contained vinegar eels for months, you will be fine!

If you have been the victim of the resilient vinegar eel, all you have to make sure of is that your new culture is eel-free, and that you have sterilized all of your kombucha items thoroughly. Remember: do not use any anti-bacterial soap, even in this situation, as antibacterial soap is harmful to the bacteria within the SCOBY. Even anti-bacterial soap residue can have a harmful effect, so definitely best to avoid.

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