Vinegar eels (Turbatrix aceti) are one of the well-known live foods used in aquarium hobby. Their small size makes them suitable for feeding most species of aquarium fish fry.

Cultivating vinegar eels is quite an easy and straightforward process that doesn’t require almost any materials. These small nematodes are tolerant of variation in acidity and they easily subsist on yeast, oatmeal, white bread, etc. or to be precise they feed on the vinegar that is produced during the fermentation of these products.

This article provides comprehensive information on vinegar eels, including their life cycle, as well as different ways to culture them in an aquarium.

Vinegar Eels as Live Food

Tubatrix aceti is a nutritious live food source and is especially well-suited for fry (bettas, guppies, corydoras, killifish, etc.), which require small and frequent feedings.

One of the great things about these worms is that can also stimulate natural feeding behaviors in fish. Vinegar eels can survive for several days in freshwater, swim in the middle and upper water column instead of settling at the bottom, and their wriggling movements stimulate the fry to eat more and grow quickly.

However, it should be noted that not all fish fry species eat vinegar eels equally well. For example, while fry of the poeciliid family may grow well on vinegar eels, fry of gouramis or angelfish may often refuse them.

These tiny nematode worms are simple to culture at home, making them a practical and affordable choice for fish owners wishing to feed their pets a natural and healthy diet.

Even though vinegar eels are a good food source, they are nutritious as baby brine shrimp (which are naturally endowed with yolk sacs), and they can only serve as a supplemental food source. They should not be the sole food source for your pets. A varied diet is essential to provide all the necessary nutrients for the proper growth and development of any animal.

What are Vinegar Eels?

Vinegar eels (Turbatrix aceti), also known as micro worms, vinegar nematodes, or nematodes, is a species of free-living roundworms belonging to the Panagrolaimidae family. They can commonly be found in unpasteurized vinegar, beer mats, and slime from tree wounds.

They and not actual eels.

These worms are harmless and do not affect the quality or safety of the vinegar they are found in. In fact, some people believe that the presence of vinegar eels in homemade vinegar is a sign of its authenticity and natural fermentation process.

Description of Vinegar Eels

Like all roundworms, vinegar eels have a cylindrical and narrow body. The anterior end is rounded, while the posterior gradually tapers off. The cuticle covering the body appears smooth. The size of the oral cavity is relatively small.

The length of the esophagus is 1/9 of the total length of the female and 1/7 of the male. The female’s genital opening is located behind the middle of the body. The spicules (male bristles that play a role in copulation) are long, thin, and curved. The length of the female is 2 mm and that of the male is about 1.5 mm.

Size: Vinegar eels are very small, typically measuring between 1/16 inch (1.5 – 2 millimeters) in length.

Shape: They have a long, slender, and cylindrical shape.

Color: Vinegar eels are transparent, which makes them difficult to see in clear vinegar.

Movement: They move with a snake-like motion, which is how they earned the name “vinegar eels.”

Live Cycle of Vinegar Eels

The life cycle of Tubatrix aceti is relatively simple and consists of four stages: egg, larva, juvenile, and adult.

1. Egg: The female vinegar eel lays eggs in the culture medium, which can hatch in as little as 24 hours. According to the study, females can produce up to 72 offspring.

1. Larva: The newly hatched larvae are very small and feed on bacteria in the culture medium. As they grow, they molt their skin several times and develop into the juvenile stage.
2. Juvenile: The juvenile vinegar eels are slightly larger than the larvae and have distinct body segments. They continue to feed on bacteria and grow until they reach the adult stage.
3. Adult: Vinegar eels need to molt 4 times to become mature. Generally, it takes them around 5-7 days. Vinegar eels have a sexual reproductive system. Eggs are fertilized internally

Livespan of Vinegar Eels

The lifespan of vinegar eels can vary depending on the nutrition, and environmental conditions, with females living up to 45 days and males up to 49 days on average.
Note: It was recorded that the maximum lifespan was around 120 days. 

3 Different Ways to Culture Vinegar Eels

There is no general consensus on the most productive way to culture vinegar eels for feeding fish fry. Several methods have been proposed, which are practically equally productive in terms of the live biomass of the nematodes.

1. Mixture of white bread and carrots.
2. Ground oatmeal.
3. Apple cider vinegar diluted with water.

When acetic acid bacteria ferment ethanol, they produce vinegar, a liquid primarily made of acetic acid (CH3CO2H) and water. Basically, vinegar may be made from anything that contains sugar and is exposed to air.

Method # 1: Mixture of White Bread and Carrots:

List of Necessary Items for this Setup:

1. Culture container: Plastic container with a lid (any size you want). You should also provide sufficient ventilation in the container (for example, by making several holes in the lid).
2. Lid: Anything that can cover the container.
   Note: Make sure to puncture a few holes in it beforehand using a needle to allow for proper air exchange.
3. Vinegar eels culture.
4. Apple cider vinegar. Do not use colored or flavored vinegar.
5. White bread and carrots.
6. Soft brush.

Step-by-step process:

1. Soak white bread in water, squeeze it, and place it in a container with a depth of about 1 inch (2 – 3 cm).
2. Sprinkle a little grated carrot on top.
3. Add a teaspoon of apple cider vinegar.
4. Mix it to a jelly-like consistency.
5. Add the vinegar eel culture.
6. Cover it with a lid.
7. Place the container in a dark place at room temperature.
8. Done

After a week, all of it will transform into a uniform, mushy mass.

Feeding: Feeding should begin as soon as the vinegar eels stop crawling up the walls. Generally, the culture gradually starts to deteriorate after a few weeks, which is thought to be the most convenient for harvesting the eels. To replenish an exhausted culture, simply place white soaked bread, grated apple, or carrots on top of it.

Harvesting Vinegar Eels

The presence of vinegar eels on the container walls and cover glass usually indicates that the vinegar eels have reached their reproductive peak after about 1 or 2 weeks. Turbatrix aceti reproduces quickly, and you can harvest them every few days after that.  

1. Take a soft brush and gently collect the worms from the walls of the container.
2. Prepare a small jar of water and rinse the brush with the worms in it.
3. Wait for the worms to settle at the jar’s bottom after gathering them.
4. Pour off the cloudy water once it has become entirely clear.
5. Repeat the process until the water in the jar is entirely transparent.
6. Pour the worms into the aquarium.

Tip: If you’re not in a hurry, you can also shine a light on the side of the container, and wait for (a few hours) them to move to the opposite side (vinegar eels do not like light). This way you will be able to collect even more.

Method #2: Ground Oatmeal

List of Necessary Items for this Setup:

1. Culture container: You will need any plastic container (up to 1 gallon (4 liters)) with a lid.
   Note: Make sure to puncture a few holes in the lid beforehand using a needle to allow for proper air exchange.
2. Freshwater.
3. Apple cider vinegar. Do not use colored or flavored vinegar.
4. Ground oatmeal.
5. Vinegar eels culture.
6. Soft brush.

Step-by-step process:

1. Add ground oatmeal to the plastic container.
2. Boil freshwater and pour it in the plastic container.
3. Bring it to a jelly-like consistency. The thickness of the nutrient medium should be about 1 inch (2 – 3 cm).
4. Let the mixture cool down.
5. Add a teaspoon of apple cider vinegar.
6. Add the vinegar eels.
7. Cover the container with a lid.
8. Done

Feeding: The food mixture gets liquid as the worms grow. Therefore, you need to add more food. Slices white bread, mash it, and add to the worm container. Bread will quickly absorb water and become an excellent nutritious feed for worms.

Note: After 2-3 months, the nutrient mass often becomes liquid. It means that you need to feed them, otherwise, they will stop reproducing.

Harvesting is similar to the first method. Dip the brush in a container with clean water, and shake the collected nematodes into it. After shaking, the worms fall to the bottom, and the cloudy water is drained.

Method #3: Apple Cider Vinegar Diluted with Water

List of Necessary Items for this Setup:

1. Culture container: A bottle with a long neck will be ideal. However, it can be done in any plastic bottle.
2. Freshwater.
3. Apple cider vinegar. Do not use colored or flavored vinegar.
4. One small, firm apple.
5. Vinegar eels culture.
6. Filter floss (or sponge).
7. Rubber band.
8. Paper towel.
9. Pipette (or dropper).

Step-by-step process:

1. Remove the peel from the apple (to avoid contamination) and slice it into pieces that can fit through the neck of the bottle.
2. Add the sliced apple to the bottle.
3. Mix the water and vinegar in a 1:1 ratio.
4. Leave a gap for airflow. Do not fill the bottle to the end.
5. Place the bottle under bright light.
6. After 10-14 days, add the vinegar eel culture.
   Note: You will notice that by that time, the water become cloudy, indicating that enough bacteria have developed in the prepared medium to introduce vinegar eels.

Many aquarists prefer to add vinegar eels right away rather than waiting for the necessary environment to be ready for them. Of course, everyone is free to do as they wish, but it has been noticed that the growth and survival of these worms are significantly higher in a prepared nutrient-rich environment.

7. Use a rubber band to secure a piece of paper towel over the bottle openings. It will allow the vinegar eels to breathe and also keep pests out.
8. Place the bottle in a dark place (or use a black polyethylene bag) at room temperature.
9. After 3 – 4 weeks, there will be enough vinegar eels to harvest.

Feeding: This setup does not usually require feedings for at least 5-6 months. After that, the colony of vinegar eels will start gradually declining. Nonetheless, if signs of depletion are detected, add a piece of apple.

The best thing about this method is that the culture requires no maintenance for months with no ill effects. The main downside though is that it also requires more time for the culture to be ready for harvest.

Harvesting methods:

• Place filter floss (or sponge) into the bottle’s neck and let it soak in vinegar. Add dechlorinated tap water (chlorine can kill them) to completely fill the bottle and wait for 12-24 hours. The water is less dense than the vinegar solution, so it will stay on top. The vinegar eels will swim through the filter floss into the freshwater for oxygen, allowing you to collect them using a pipette and feed them to your fish fry.
  You can attach the floss to a fishing line. So, if you push it down it will be easy to get back.
• Use a coffee filter. Pour the mixture into it. Rinse afterward. Place it upside down in a cup of tank water, swish it, and then pour it into the tank.
• Take a piece of sponge and tie it with a fishing line or a zip tie. Soak the sponge in the solution for a day, then remove it using the fishing line or zip tie and rinse it with dechlorinated water. You will find a large number of worms inside the sponge.

 Tip: It is advisable to culture them in several bottles, in case of any unforeseen circumstances.

Maintain Rules to the Culture Vinegar Eels

The culture container should be placed in a dark, warm place for the vinegar eels to grow, ideally between 64-71°F (18-22°C).

According to the study, these worms do not like warm temperatures. For example, as the temperature increased from 60 – 97°F (15 to 36°C), the survival time and lifespan of Turbatrix aceti greatly decreased. In fact, at 122°F 50°C), the survival time was only 20 seconds.

Although these nematodes prefer an acidic environment, their growth and survival rate significantly drops at pH 3.75. The growth rate is greatest when the initial pH is between 4.5 – 6.5

Note: The low pH at which this species is maintained proved to be useful in preventing bacterial contamination.

Keep the culture medium moist by adding a small amount of water or vinegar as needed. You can also gently swirl the container to mix the worms and the medium.

Where to get Vinegar Eels?

Actually, it is not that difficult. You can typically find vinegar eels for sale online through various retailers. It is also possible to find them for sale through online marketplaces like Amazon or eBay.

Keep in mind that unpasteurized apple cider vinegar occasionally contains vinegar eels. Therefore, you might be able to get them by establishing a culture from a bottle of this vinegar.

In Conclusion

Overall, vinegar eels are a great live food alternative for fish owners wishing to feed their pets a balanced, organic diet.

They are a valuable addition to any aquarium because they are not only a wholesome food source, but they can also aid in stimulating the natural eating activities of fish.

Culturing vinegar eels is extremely easy and can be done at home with minimal equipment.

Vinegar eels as Live food
Pros	Cons
Very easy to culture	Suitable only for small fry
Good nutrient content	Other live foods are more nutritious
Stimulate natural feeding behaviors in fish
Can live in freshwater for several days
Stay in in the middle and upper water column

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References:

1. Kahn, Monica. “An in vivo study of the effects of [alpha]-tocopherol on the free-living nematode turbatrix aceti.” PhD diss., Concordia University, 1980.
2. Anguillula aceti: Print. The free-living nematode Panagrellus redivivus (common names include vinegar eel, vinegar eelworm, vinegar nematode, paste worm, starch worm, sour paste nematode, sour paste eelworm, beer felt nematode, and beer mat nematode). Universal Images Group / Getty, Zugriff 20. Okt. 2021
3. Vogel, Kathryn G. “Temperature and length of life in Turbatrix aceti.” Nematologica20, no. 3 (1974): 361-362.
4. Kahn, M., Enesco, H.E. Effect of α-tocopherol on the lifespan of Turbatrix aceti. AGE 4, 109–115 (1981).