VINEGAR EELS:† SEPARATING MYTHS FROM FACTS.† Or, how the hell do you get the little suckers out of their culture?
Peter J Unmack
Over the years I have heard many sorry tails from people who tried to culture vinegar eels.† Or more to the point, how they tried in vein to collect them from the culture.† Other people thought they were just too much trouble.† Vinegar eels have many advantages to other foods for fry.† They are very easily cultured, collected, and you cannot overfeed your fish on them unlike APR and other dead foods, because the vinegar eels will live quite happily in you aquarium until your fry eats them.†
The Critter.† What is a vinegar eel?
Vinegar eels (Turbatrix aceti) belong to the phyla Nematoda, otherwise known as namatodes.† Many aquarists have come across flatworms at one time or another when they have allowed too much crud to build up in their tanks.† One ends up with thousands of little white worms crawling all over the glass in their fish tank.† You can rest assured your vinegar eels will not cause this problem.†
What to feed vinegar eels to.
Vinegar eels typically reach about 3mm or 1/8in.† This makes them an ideal size for feeding to fry that are a little bit too small for baby brine shrimp.† The other important consideration is that vinegar eels tend to congregate near the surface of the water.† Thus, they are of little benefit to fry which live on the bottom.† I have successfully used vinegar eels to as a first food to raise rainbows, blue eyes, hardyheads, and peacock gudgeons.† No doubt they work well on other fry, these are just the ones that I have tried.†
How to culture them.
First of all get two broad necked jars.† The reason for having two is that if one crashes and dies you still have another to fall back on.† They can be plastic or glass, as long as they are transparent (so you can see the little critters).† I usually get something like a 1/2 gallon plastic coke bottle and cut the top of it.† The size of the container doesnít really matter, you can culture them in anything, however, you can harvest more from a larger culture.† The next required item is the culture medium.† This consists of cider vinegar and water.† Most recipes recommend a 50 50 mix.† I have used everything between 20% vinegar or 80% vinegar, I donít believe there is a significant difference between them.† Once you have all this, you can add the vinegar eels your good buddy generously donated to you so that they may set forth and multiply in your culture.† Many people recommend the addition of apple or sugar.† I have never personally used apple, thus I cannot comment on whether or not it is beneficial.† However, I have found the addition of sugar to be useful if I needed to get a culture up and running quickly.† You will get higher densities of vinegar eels in shorter time.† However, I have found that the culture will not last for as long, and you tend to get a thicker scum on the surface than normal (normal being the addition of nothing).† For regular usage I donít recommend adding anything to the culture.† The temperature doesnít seem to matter.† I have had them reproducing at temperatures between about 60-85oF, no doubt they will reproduce in wider extremes.† It is not necessary to cover the culture.† However, this will reduce evaporation and keep dust and other items like bugs and air stones from falling into the culture.† The culture should be viable for a minimum of three months or so, even with the addition of sugar.† They have been known to go for several years.† I would recommend cycling the cultures, that is, space out starting each culture by a month or two.† That way you will never be caught short of worms when you least expect it.† Never rely on one culture.† It will let you down, just ask Murphy.† When a† culture dies it usually turns black with no cloudiness.†
How to tell if there are any eels present.
First of all you require good eyesight.† If you are visually challenged then the use of a magnifying glass may be helpful.† The best way to see them is to hold the culture up in sunlight (itís far easier to see them in sunlight than artificial light).† At a glance, the culture itself will look cloudy.† Try to focus onto the individual specs within the cloud and you should see millions of tiny squirming worms.† An alternative to this is to suck some of the culture up in a glass eye dropper and view them as above.† Once you recognize what you are looking for they become very easy to spot at a glance.
The million dollar question.† How to get them out of the culture.
Extracting vinegar eels from their culture is exceptionally simple.† Never, ever, pour your culture through a coffee filter or anything else, it is just too labor intensive, messy, and not very effective.† All you need to do is hang something porous in the culture.† In Australia, we usually use a plastic coffee filter.† Unfortunately, I have not seen these available in any supermarkets in the western USA.† Your imagination as to what to use is the only limit.† Just keep trying different things until you find one that works best for you.† In the absence of a plastic coffee filter I would use the abrasive (usually) green side of a sponge used for cleaning the dishes (obviously buy a new one and rinse it well first).† The reason why I would use an abrasive sponge rather than a regular sponge is that the culture medium will drain out of it fairly thoroughly without having to squeeze it.† You shouldnít have to get your fingers wet.† I would poke an ice-cream stick through one end of the sponge so that you can hang it in the culture.† You only need about 1/2 an inch of sponge hanging in the culture as most of the vinegars eels are at the surface.† To feed your fish just lift the sponge out and allow it to drain.† Vigorously swash the sponge in some water and you have your eels ready to feed to your fry, just pour it into their aquarium.† Hang the sponge back in the culture and you are ready for next time.† One thing to be wary of is that you will transfer very small amounts of vinegar to your aquarium which will drop the pH.† To counter this I add some sodium bicarbonate to the water I swash the sponge in containing the vinegar eels once every few days.† As I pour this into the various fry tanks it buffers the tank from acidic conditions.† You do not need to be too concerned about making your tank too alkaline.† Most Aussie fish can tolerate a high pH, (say 8) and sodium bicarbonate cannot raise the pH up over 8.2 no matter what concentration you put in the aquarium.† Trial and error over a couple of weeks will soon teach you how much to add without making the pH too high.† I have tended to over stress this problem just so that people should be aware, it is really not that bigger deal.† Most people I know donít worry about it all and they have no problems.†
The greatest advantage to my mind with vinegar eels over APR is that it is a live food.† You cannot overfeed your fry.† They will survive for long periods of time in the aquarium and they can tolerate high pH.† I usually add copious quantities of vinegar eels in with the fry.† When I can hardly see any left then I add some more.† That way the fry always have food available to them to eat.† Irrespective of which foods you feed it is important to remember that a diversity of foods is always best.† Happy eeling!
Reprinted from The Rainbowfish Times, journal of The North American Rainbowfish Study Group. Volume 9(3): 15-17.† 1996.