Feeding Breeding How-to guides Video

How to culture Vinegar Eels – Fry food!

vinegar eels 1

Feeding fish fry need not be difficult. Vinegar eels are easy to culture and a single supply can last forever. This article will cover how to set up a simple vinegar eel farm and how to harvest them to feed to your fishy babies.

Vinegar Eels – Fry Food

How to feed fish fry is a common concern for aquarists, particularly if you haven’t bred fish before.

With the fry of many species being so tiny, they can be difficult to feed, especially as their natural instinct does not tell them that flakes and pellets are food.

So what do we feed them?

You will find a few options within our posts, but here is another, Vinegar Eels! They’re easy to keep and a great choice as Fish Fry food.


What are Vinegar Eels?

Vinegar Eels are nematodes, or in plain language, tiny little worms – not actual Eels! They are so small that they are almost invisible (unless you’re looking for them) and appear to be white in colour.

Vinegar Eels are ideal for feeding fish fry, as they are easy to keep and to culture. This makes them a good option when considering foods for your newly hatched fish fry.

Growing to a maximum of 2mm, they are perfect for feeding tiny fry from smaller fish such as Betta or Tetra. The fact that they wriggle initiates the fish’ instinct to eat far more effectively than a flake of dried food does.

Vinegar Eels get their name as they were originally discovered living in unfiltered Vinegar. These days, Vinegar tends to be filtered so these guys no longer make it onto your chips.

The easiest way to get a culture going is to buy a starter culture online. A starter culture usually costs around £3 and will potentially provide you with a never-ending supply of fry food.


Vinegar eels fish fry 1

(My current culture ready for a harvest)

Growing a culture of Vinegar Eels

Once you have a starter culture growing it is relatively simple.

What you will need:

  • A container, or two.
  • A bottle of Apple cyder Vinegar.
  • A long-necked bottle/vase – can be the bottle the Vinegar comes in.
  • A bit of apple and a spoon of sugar.
  • Some dechlorinated water.
  • Some cotton or foam – filter pad will work.


As mentioned previously, Vinegar eels are often found living in Vinegar. This is because they feed on the yeast culture and bacteria that is used to make vinegar.

The Apple Cyder vinegar is what they will live in and feed on. With a little apple and sugar to top it up.


Setting up a Vinegar eel culture

To get your culture growing, you will need to add your Apple Cyder Vinegar to a container, mixing 2 parts Vinegar to 1 part dechlorinated water.

The container you choose is entirely up to you, wide containers are the best for growing a culture as they provide more surface area, but a long-necked bottle is ideal for harvesting your Eels. Having one of each is ideal.

Next, add a few slices of apple and a teaspoon of sugar to your mix. This will provide some additional food for your Vinegar Eels.

Now add your starter culture of Vinegar Eels.


You may notice fairly quickly that you can see the Vinegar Eels at the surface of the liquid. They need access to the surface for gas exchange (breathing) and this is why a wider tub, such as a Tupperware container, is ideal for growing them in.

In this little set-up, Vinegar Eels will breed away and your culture will last indefinitely. They don’t require any light, added nutrients, or anything else. They only need to be kept at room temperature or slightly cooler for the best results.

If you breed fish regularly and need to feed fry quite frequently, having more than one culture growing is a great idea. This means you can alternate between them providing a constant supply of fresh fish food.

This means that for the cost of around £6, you potentially have an indefinite supply of fry food. Not bad economy.


Vinegar eels 3

(Photo from the Aquarium Co-op – video below)


Harvesting Vinegar Eels

Once your Fishes eggs have hatched and your fry are free swimming, it’s time to start feeding them up on your Vinegar Eels.

Now, the issue here is that pouring Vinegar into your fish tank isn’t going to do a whole lot of good and is potentially very dangerous to the fry you are trying to raise. So we need a way to separate the Vinegar Eels from the Vinegar.


Harvesting Vinegar eels

This is where the long-necked bottle or Vase comes in handy.

If your culture is not already in a container like this then pour it into one so that the mix fills partway up the neck of the bottle. If it is in one already then simply top up the mixture with Apple Cyder Vinegar so that it reaches this level.

The neck of a bottle or vase is really useful for harvesting Vinegar Eels quite easily. By stuffing a piece of foam, such as part of a filter pad into the neck you are able to almost place a lid on the vinegar, but a lid that Vinegar Eels can pass through.

It’s handy to have a good pair of mini-tongs for this as they will make it a little easier to keep hold of the foam. I regularly end up with a bottle full of foam pieces that I’ve pushed too far down and can’t get back out! I get there eventually though.

Once your foam is in place (just above the surface of the Vinegar) with no air bubbles underneath, (push the foam down and pull back up to release the bubbles). Gently add some tank water to the top of the bottle. You will notice that it remains clear and does not mix much, if at all, with the vinegar.

As the Vinegar Eels need access to the surface, they will slowly find their way to the top of the bottle and into the area of freshwater you have created.

From here, they are easily harvested using a pipette. This water should contain so little vinegar that it can be added straight to your tank with the Vinegar Eels. Once harvested, replace the water ready for the next collection. This can continue until either the Vinegar Eels are used up from that culture, or you no longer need to feed them to your fry.


So, just in case any of this was confusing, or difficult to picture. Here’s a video I found of this method in practice on Youtube from the very popular Aquarium Co-op:


The Aquarium Co-op run a very popular Youtube channel and run an online shop in the USA.

To see more of their Youtube content, Click here.


Happy Vinegar Eel growing! Let us know how you get on in the comments!


vinegar eels fish fry

(Amatitlania Myrnae fry awaiting their Vinegar Eels)



The Science of Vinegar Eels – Ripleys.com

Aquarium Co-op video- Youtube.com

About the author

James @Seriously Fishy

I am a fish keeping enthusiast with over 20 years experience. I currently keep American Cichlids (CA) which are my favourite fish to keep so far. I started Seriously Fishy as I noticed a large volume of people on various web pages looking for help with Aquarium basics. I created the first Seriously Fishy book to solve the issue in 28 pages, that led to the Seriously Fishy UK fish forum and blog.

Leave a Comment