Vinegar eelworms (Turbatrix aceti) are free-living, non-parasitic roundworms that are adapted to living in a low pH (acidic) medium and are an excellent live food for rainbowfish fry. They are readily cultured in large numbers, provided certain simple procedures are followed. They must be grown in natural cider 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 necessary.
Add your eelworm culture to approximately 500 mil 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 eight days from time of fertilisation of the egg to time of birth of the young.
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 fry tank. The most common method to harvest the worms is to pour or siphon the culture medium through a laboratory or coffee filter paper and in so doing collect most of the worms. Return the medium back to your culture container. The filter paper with the collected worms is then rinsed into a jar of clean aged water and can then be poured into the fry 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 only drawback with vinegar eelworms is the harvesting method required.
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.
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.
© Copyright Adrian R. Tappin
Updated September, 2002.
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