What vinegar eels are
Vinegar eels (Turbatrix aceti) are free-living nematodes that feed on the bacteria and yeast of “mother of vinegar” and turn up in unfiltered vinegar. They are harmless and not parasites. Breeders feed them to fry the same way as microworms; they are thinner than microworms and swim up in the water instead of sinking, so fry can find them for longer.
Starting a culture
- Mix equal parts apple cider vinegar and dechlorinated water in a clean jar or bottle.
- Add a few thin slices of apple.
- Pour in a starter culture from a breeder, a fish club or a shop.
- Cover the top with a paper towel held by a rubber band, so air gets in and flies stay out, and keep it at room temperature.
It takes a few weeks to thicken: hold the jar against the light and look for a faint shimmer of tiny moving threads.
Getting them out of the vinegar
Pour some culture into a long-necked bottle, plug the neck with filter floss and top it with dechlorinated water. Over a few hours the eels swim up through the floss into the clean water, which you can pour off for the fry. Or strain some culture through a coffee filter and rinse the eels off it into a cup of tank water. Either way, the vinegar stays out of the fry tank. Feeding fry
Keeping it going
A vinegar eel culture lasts for months with almost no work. Top it up with a little vinegar and water and a fresh slice of apple every month or two, and start a second jar from it as a backup.