After getting a successful spawn, you want to get your fry off to the best possible start to ensure getting them to adulthood. With Bettas, that means having live food small enough for them to eat and having it available as soon as they are ready to eat. Vinegar eels are a very good first food for young fry because as live foods, they are readily accepted by newly free swimming fry. They are also very easy to culture and feed and can get your young fish off to a good start before starting to feed baby brine shrimp or a micro pellet. Not only are they small in size, but they also stay alive in the water longer than other first foods, giving the young Bettas time to eat them before they die off and start fouling the water.
Setting up Your Culture
Once you get a starter culture you need to get it going and established. Usually you will get a few ounces of a vinegar mix with the worms in it. The best way to do this is to create a main base and then another container you harvest out of. I have my main culture or base in a glass honey jar.. see photo. The worms live in a vinegar mix that is half apple cider vinegar and half water mixed. I have used both Reverse Osmosis water as well as tap without water conditioner and both have worked equally as well. So, mix up some of the vinegar mix and put it into a good-sized container that you will use as your base culture. I have used 2 liter soda bottles and a gallon pickle jar. There is no right or wrong, use what ever you have handy. Once you get your base container add the vinegar mixture, your starter culture and some sugar. Fill up a good 2/3 of this container so you have a good volume of culture to work with. In a jar sized like the soda bottle or pickle jar you can add a teaspoon to the mix for the eels food source. Again, there is no right or wrong, you can pretty much just dump some in. Many people use cut up apples, but I found that a bit too messy. So use sugar because it is quick and easy and always available.
After the base is set up, put the eels some place and forget about them a bit. Someplace out-of-the-way is ideal. I have enough cupboard space I keep the base container in one of them. You also might want to stretch a paper towel across the top and rubber band it so the eels have air and gnats, that LOVE the vinegar mix, don't wander in and end up in the culture. In a very short time, the eels will multiply nicely. Depending on the size of your starter culture they should have reproduced enough to get a modest harvest and/or get your harvesting containers going in a few weeks.
Once you get some good numbers in the eels you want to set up a container of them for harvesting. I use long neck bottles for harvesting. We got some flavored drinks in this type of bottle and a friend saved some wine cooler bottles. To this bottle add some of the cider mix and a "start" of your base culture. Add some sugar and again, set aside for a few weeks to multiply before harvesting. Every spawn will take one harvest bottle, so if you have multiple spawns, set up multiple harvest bottles. I often have several spawns at one time so I need to have several bottles to harvest from at any given time. So I maintain my base and start up several bottles to harvest from. If you need to harvest eels for a spawn as soon as you get your culture, put most of the starter in the harvesting bottle and a small start in the base container. Add sugar and set it aside to get established Harvesting will pretty much wipe out the population of eels in the bottle, so you want to get that base going so you have more eels in the future.
Harvesting the Eels
To harvest the worms you want to bring the vinegar mix up into the neck of the bottle. I keep an old vinegar bottle with the half and half mix so it is handy. Bring the level up into the neck like in the bottle in the first picture next to the honey jar. Then take some filter floss and wrap a twisty tie around the middle and stuff it down into the neck of the bottle so it comes into contact with the vinegar mix. Curl the top of the twisty tie around and down like in the photo. This will allow you to pull up the floss when you are done harvesting. Twine will not work as it will wick the vinegar mix and it will end up all over the counter. The twisty tie works great and are pretty easy to get.. at least around my house.