How to Culture Vinegar Eels for Fish Fry

Are you getting into fish breeding but need a way to feed teeny-tiny fry that are too small to eat regular fry food? Vinegar eels might be a good choice! This live food is easy to cultivate and is great for raising babies, until they are old enough to eat baby salt shrimp.

What Are Vinegar Eels?

Vinegar eels, which are either white roundworms (or nematodes) that feed on microorganisms found in vinegar and fermented beverages, are harmless. Growing up to 50 microns in diameter and 1 to 2 mm in length, they are one of the smallest and easiest live foods to culture for baby fish. Breeders commonly feed them to newborn betta fish, killifish, rainbowfish, and other fry that require miniscule foods even smaller than baby brine shrimp (which hatch out at 450 microns in size).

Vinegar eels are great for feeding fish fry. They can live for several days in freshwater, unlike banana worms or other microworms. Their wiggling motions attract babies to eat more, grow faster, and swim in the water column, rather than sinking to the bottom like microworms. Vinegar eels aren’t necessarily as nutritious as baby brine shrimp (which are born with rich yolk sacs), but they’re an excellent food to feed until the fry have grown large enough to eat baby brine shrimp.

How Do You Start a Vinegar Eel Culture?

1. Gather the following materials:

– Starter culture of vinegar eels (from local fish auctions or online sources like aquabid.com) – 1 container with a long neck (like a wine bottle) – 1 backup container (like a 2-liter bottle or 1-gallon jug) – Apple cider vinegar (enough to fill half of each container) – 1 apple – Dechlorinated tap water – Filter floss or polyester fiber fill (stuffing for pillows and stuffed animals) – Paper towels – Rubber bands Pipette – Optional: funnel

1. Cut the apple into thin slices that can fit through the container openings, and then put four to eight slices in each container.

1. Divide the starter culture of vinegar eel into each container. 2. Fill the rest of the containers with 50% vinegar and 50% dechlorinated tap water, such that the total liquid amount reaches the base of the bottle’s neck. (Leave a little space at the top of the containers for air.)

1. Cover the container with a sheet made of paper towel. Secure it with a rubberband. This allows the vinegar eels to breathe while preventing pests from entering. Keep the containers at room temperatures in a cabinet, or on a shelf that doesn’t get direct sunlight.

The wine bottle is your primary culture and can be used to harvest vinegar eels. In case the wine bottle is damaged, the larger container can be used as a backup culture. You can leave backup cultures alone for up to a year without feeding them. The population may decline a little, but you should still have enough vinegar eels to start a new culture if needed.

How Do I Harvest Vinegar Eels to Feed My Fish?

1. Allow the wine to sit for at least two to four more weeks before you start feeding the fry. 2. When you are ready for harvesting, insert a wad if filter floss into the neck. The floss should be soaked in vinegar.

1. Gently pour some dechlorinated water into the bottle’s neck.

1. Wait for 8 to 24 hours and the vinegar eels can travel through the filter floss to the freshwater to get oxygen.

1. Take some of the vinegar-eels out with a pipette, and give them to your fish fry.

You can use this method to feed for several days in a row, maybe up to a week, but eventually the culture will start to deplete. Therefore, if you have lots of fish babies, prepare several bottles of vinegar eel cultures so that you can rotate between them, giving each bottle four to five days between feedings so that the culture has time to repopulate.

How Do I Maintain the Vinegar Eel Culture?

Around the six-month mark, the apple pieces eventually break down, the nutrients are used up, and you may notice the culture is much cloudier than usual. This is the time to start a fresh culture. Get a new container, and pour in some of the old culture. Fill the rest of the new container with apple slices and a fresh mixture of 50% apple cider vinegar and 50% dechlorinated water. Within two to four week, your new culture will be ready for harvesting.

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