Turbatrix aceti, formerly known as Anguillula aceti and colloquially as the vinegar eel, wine eel or vinegar worm, are small (1~2 mm) free-living, non-parasitic roundworms that feed on bacteria and yeast that cause fermentation in vinegar. They are adapted to living in a low pH (acidic) medium and are an excellent live food for freshwater fish larvae. Although vinegar eelworms live best in an environment of weak vinegar, they can be cultured in a variety of different media such as apple cider and 4% sugar in water. It is the sugar rather than the acetic acid which appears to be the essential element of the medium. Turbatrix aceti is often found in great numbers in vinegars made of apples or other fruits, or in other fermenting substances. The nematode is free-swimming in the liquid, reaching high individual numbers at the surface, where the oxygen concentration is higher, and are constantly in motion.
Vinegar eelworms are readily cultured in large numbers provided certain simple procedures are followed. They must be grown in natural cider vinegar or Balsamic vinegar that has not been chemically treated to inhibit growth of bacteria and yeast upon which the worms feed. The vinegar can be used either pure or diluted with 25 to 50% water. The periodic addition of a small amount of apple juice seems to add something that causes a greater population of worms, but is not absolutely necessary.
Add your eelworm culture to approximately 500 ml of culture medium in a wide-mouth glass jar covered to reduce evaporation. Punch small holes in the lid (cover) for aeration. Cultures should be maintained at 20~30°C and subcultured every 6~8 weeks to fresh medium. Vinegar eelworms can rapidly increase in number and females with developing embryos can be found within one week of starting a new culture. Embryonic development takes about 7~10 days from time of fertilisation of the egg to time of birth of the young. The larvae become sexually mature in about 28 days. Median life span of vinegar eelworms varies with temperature, from 55 days (25°C) to 40 days (30°C). The maximum life span has been reported as 10 months.
Harvesting of the worms may test your patience until you have developed a procedure to collect them, as it is very important not to get any culture medium in the fish larvae tank. The most common method to harvest the worms is to pour or siphon the culture medium through a laboratory (1.2 µm) or coffee filter paper and in so doing collect most of the worms. Filters with larger pore sizes would probably be better as a small pore size captures more debris. Return the medium back to your culture container. The filter paper with the collected worms is then rinsed into a jar of clean freshwater and can then be poured into the larvae tank. The eelworms will live for a long time in the tank but care should be taken to prevent supplying too many worms at one time. Starter cultures can be obtained from biological supply companies, aquarium shops, or fellow hobbyists.
The advantage of feeding vinegar eels is:
Vinegar eels will live for a long time in the aquarium water.
Vinegar eels swim in the water column and stay towards the surface where rainbowfish fry feed.
Vinegar eels are just a little smaller than micro-worms, a great size for most baby fish.
Vinegar eel cultures require little attention (indeed they can be ignored for weeks at a time)
Vinegar eel cultures don't "go off" leaving an unpleasant smell.
The only drawback with culturing vinegar eelworms is the harvesting method required. Several methods of concentrating the organisms and washing to free them of the bulk of contaminating organisms have been reported. Some culturists separate the worms from the vinegar in small test tubes. Culture medium on the bottom; some filter floss, and clear water on top. The worms seeking oxygen move up through the filter floss to be near the surface. Very effective, but not enough worms to feed many fry.
A modified technique using the same theme but productive enough to be useful is to use longneck bottles for culturing. Keep the culture medium level well below the neck to have adequate surface area. To harvest, remove the floss plug and add enough spare culture medium to reach above the bottom of the narrow neck. Push the polyester filter floss down to the surface. Add fresh water up to the top of the neck. In a few hours (or overnight), there will be a rich collection of eels in the fresh water, but no noticeable mixing from the vinegar below. Collect the worms with a bulb baster or dropper. Remove the floss and squeeze dry. Pour enough vinegar back into a spare bottle to get good surface area again in the main culture bottle and loosely plug the top of the neck with the damp floss.
A more technical method depends on the negative geotropism of the vinegar eels. The culture is concentration in a separatory funnel. Most of the organisms will, within a few minutes, aggregate at the surface of the liquid in a dense layer 5~8 mm or so deep. The lower liquid is drained off rapidly. The concentrated suspension remaining is poured into burettes (50 or 100 ml.). After a few minutes the lower portion of the burette will contain few worms and the organisms will have begun to aggregate at the surface. The stopcock is opened slightly and the liquid allowed to drain out drop wise at a rate which will leave the surface-aggregated organisms behind, adhering to the wall of the burette. If the outflow rate is properly adjusted, most of the vinegar eels will remain on the walls of the burette when the liquid has drained out. The worms are rinsed from the burette with a small amount of a suitable solution. When a sufficient number of worms have been collected they may be washed any desired number of times by repetition of this procedure.
© Copyright Adrian R. Tappin
Updated December, 2008.
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