Vinegar Eels (Turbatrix aceti) are free-living nematodes that feed on the microbial culture, called the mother of vinegar used to create vinegar. They are non-parasitic unsegmented roundworms, discovered by Borellus in 1656. They eat bacteria and fungi that grow in unpasteurized vinegar solutions. Vinegar eels live an average of 10 months, giving birth to as many as 45 young every 8 to 10 days. A healthy culture can experience a 20-times increase in its population in only 8 days. They thrive over a wide range of temperatures from 15°C to 32°C. In pure liquid cultures, such as a mixture of apple cider vinegar and apple juice, 90 percent of the worms will inhabit the top 6 – 7 mm of the liquid to be as close to the oxygen-rich surface as possible. Their favorite congregating location is the thin meniscus at the edge of the liquid/container interface.
Vinegar eels typically reach about 3 mm. This makes them an ideal size food for fry feeding that is a little bit too small for baby brine shrimp. The other important thing is that Vinegar eels tend to congregate near the surface of the water, which makes them a perfect first food for the fry of top dwelling species. Vinegar eels are really good as the first food to raise Rainbows, Blue Eyes, Gudgeons, Betta, Killifish, etc.