Vinegar Eel Culture as Live Fish Food: The Ultimate Guide


What is a Vinegar Eel (Turbatrix aceti)

Vinegar eels are not eels but rather non-parasitic nematodes that live in unpasteurized apple cider vinegar. They are a popular type of live fish food for feeding fish fry and small juvenile fish. One of their advantages as a food source is their small size and ability to survive in water for days until they are eaten.

Characteristics of Vinegar Eels

Vinegar Eels are usually between 1 and 2 mm long. When they collect in large numbers at a liquid boundary they will synchronize their swimming movements into a long undulating wave. Under a microscope they appear as long transparent tubes with visible digestive tracts. Growing cultures of vinegar eels smell sour, and must be covered to avoid infestation by insects such as fruit flies.

Use of Vinegar Eels as fish food

Vinegar eels are a common and cheap way to feed small fish fry which can only consume tiny foods. They are simple to grow and colonies can hold for weeks before being harvested for food. This makes vinegar eels an easy and forgiving fry food for fish breeders.

Use of Vinegar Eel to feed newborn fish fry

Vinegar Eels are a great choice for any fish fry which need tiny foods. Brine shrimp are another common fry food, but some fish fry are so small they have difficulty eating any but the smallest baby brine shrimp. Vinegar eels are a popular first food for these tiny fish fry. They are particularly popular with Betta breeders but can also be used for Tetra and Rasbora fry.

Vinegar Eel (Turbatrix aceti)
Vinegar Eel (Turbatrix aceti). Alfredo Eloisa. CC BY-NC-SA 2.0 / Edited from original

What are the benefits of Vinegar Eel as fish food

Vinegar Eels can hold for weeks and be ready to harvest within 24 hours. They also will live and move in water longer than some other common fry foods such as baby brine shrimp and microworms. Unlike some of these other foods, vinegar eels can live for up to a week which gives tiny fry lots of chances to eat them. One downside is that vinegar eels aren’t as nutritious as brine shrimp. Baby brine shrimp have egg sacs which can make them a more nutritious meal for fish fry.

Are Vinegar Eels harmful to humans?

Vinegar Eels are not parasitic and are harmless to humans. You could even eat them, but you probably don’t want to.

How to Culture Vinegar Eels

Vinegar Eels are one of the easiest fish foods you can cultivate. While they aren’t as nutritious for fish fry as brine shrimp, they are very forgiving and batches can live for weeks at a time. This long holding time comes in handy when you aren’t sure of the exact time you’ll need to feed fry. Once a batch of vinegar eels has passed their initial growth period of 2 to 4 weeks, they will keep for a couple of months until needed for fish food. If you have fish you are planning to breed it’s a good idea to have a few batches of vinegar eels on hand when the time comes to feed you fish’s fry.

1. Assembling your vinegar eel growing equipment

The basic things you’ll need to start cultivating vinegar eels are: vinegar eel starter culture, glass bottles with long thin necks, unfiltered apple cider vinegar, non-chlorinated water such as bottled or RODI, apples and breathable bottle covers which can be paper towels or coffee filters. When you’re ready to harvest your eels you’ll need filter floss and a pipette. It is important for your growing containers to have a long thin neck, wine bottles are a perfect choice here. This is needed when harvesting as you’ll force the vinegar eels up into this thin neck for easier removal with the pipette.

2. Preparing a growing container for vinegar eels

Peel and slice the apples so the wedges are small enough to pass through the necks of your growing bottles. Thoroughly clean all bottles and add 4 or 5 apple slices. Now add your vinegar eel starter culture and fill with a half-and-half mixture of unfiltered apple cider vinegar and non-chlorinated water. This mix should come up to just below where the bottle’s neck starts but shouldn’t extend further up the neck. Top the bottles off with a paper towel or coffee filter and hold this down to the neck with a rubber band. This allows your cultures to get air but will prevent insects and dirt from entering the bottles.

It’s difficult to give a definite recommendation of how much starter culture to add. This depends on the health of the culture and how long you are willing to wait to harvest your vinegar eels. Starter culture won’t last for long so there isn’t much point in holding back a portion of the batch. Once your vinegar eel cultures are growing, it’s easy to start another batch whenever you want. If you are needing lots of fry food you’ll probably have multiple batches at different stages of growth and won’t have much use for prepared starter culture.

Apple Cider Vinegar is used to culture Vinegar Eels
Apple Cider Vinegar is used to culture Vinegar Eels

3. Growing and splitting batches

Once your containers are prepared, leave them to sit in an area away from direct sunlight. It usually takes between 2 to 4 weeks for a vinegar eel culture to grow enough to harvest. Once this time has passed, a culture will last for a couple to a few months. Eventually the vinegar eel population will start to reduce so you probably shouldn’t hold cultures for longer than 4 months if you plan on harvesting them for fish food. As your colony grows you may be able to see the tiny vinegar eels swimming near the top of the liquid. They are very small, so you may need a magnifying glass to see them.

You can start new vinegar eel batches from any living colony. This includes batches which you’ve harvested for food. Even a “spent” vinegar eel batch will have enough live eels to start a fresh batch. Spent batches can be rejuvenated by pouring out half of the batch, adding more apple cider vinegar and apple slices, then covering and waiting for an additional 2 to 4 weeks. Vinegar eels are harmless, so spent colonies can simply be poured down the drain.

4. Harvesting vinegar eels

When you’re ready to harvest your vinegar eels, uncover the bottle and pack a piece of filter floss in the neck. This should extend down to the level of the vinegar but shouldn’t be pushed deep enough to become saturated. Now add non-chlorinated or RODI water to the neck to bring the liquid level about an inch from the top of the bottle. Re-cover the bottles and let them sit for about 24 hours. What this does is cause the vinegar eels to work their way up through the filter floss and into the bottle’s neck to get air. After 24 hours you should see the tiny vinegar eels swimming in the neck of your culture bottle. You can now use a pipette to remove vinegar eels to feed your fish fry!

5. What to do when a vinegar eel batch is used up

Vinegar eels are harmless, so spent batches can be simply poured down the drain. If you plan on needing more fish food in the future you can split a spent batch to start new colonies. For this you only need a portion of an old batch which you’ll add to a new one in place of starter culture. If you don’t harvest, these batches can last 6 months to a year before needing to be refreshed. Keep in mind that the vinegar eel population will start to drop off after a couple of months. This is a good way to keep some vinegar eels on hand for the future and saves you from having to locate fresh cultures.

Where to Find Vinegar Eel Culture for Sale

While Vinegar eel cultures may be difficult to find in local fish stores, they are easily available online. Prices are very reasonable, usually available for sale for less than $20 USD.

Can you culture Vinegar Eel without a starter culture

If you can find unpasteurized apple cider vinegar with mother you may be able to start a vinegar eel culture without starter. Some sources indicate that apples may contain enough vinegar eels to start a healthy culture. This method has lots of complications: in many countries all apple cider vinegar sold is pasteurized. This is even the case with unfiltered apple cider vinegar. If you can find the right kind of apple cider vinegar or want to take your chances with apple slices you can attempt to grow a colony without starter culture. If it does work it will take a lot longer than normal. Starter cultures give a real boost and will get your vinegar eel colony up and ready to harvest in a few weeks. Without that helping hand expect to wait at least 4, and probably 6 weeks before seeing any signs of life.

Vinegar Eels vs Microworms

While vinegar eels and microworms are used for fish food, vinegar eels will live and move in fresh water for longer, and have a greater chance of being eaten by fish fry. Microworms sink and die much quicker. Microworms can be cheaper to cultivate as their growing medium is based on a mix of starch and yeast. Apple cider vinegar can be more expensive, especially if you are planning on growing lots of vinegar eels to feed fish fry.

Fish Laboratory

With decades of collective fishkeeping experience, we are happy to share the fish care tips that we've picked up along the way. Our goal at Fish Laboratory is to keep publishing accurate content to help fishkeepers keep their fish and aquarium healthy.

Recent Posts