Black worms and tubifex worms are two of the best live foods you can give aquarium fish. They’re packed with protein, fish go crazy for them, and they can help condition breeding fish and grow out young fish. So it’s no surprise that many fish keepers eventually ask the same question: can I just breed my own?
You can try, and in this guide I’ll show you the basic method. But I’ll also be honest with you about my own results, because I think that part will save some of you a lot of time.
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What Are Black Worms and Tubifex Worms?
Black worms (
Lumbriculus variegatus) are small, dark aquatic worms that live in the mud and decaying leaves of cool ponds, marshes, and streams. Tubifex worms are thinner, usually reddish worms that live headfirst in the mud of slow or polluted waters, with their tails waving in the water above.
Both are segmented worms related to earthworms, and both feed on bacteria and decaying organic matter. For a closer look at how they differ, see my guide
Black Worms vs. Tubifex.
If you’re going to culture one of them at home, black worms are the better choice. They’re cleaner, easier to keep, and far less likely to bring disease into your aquarium.
How Black Worms Reproduce
Black worms don’t pair up and lay eggs like fish. They reproduce mainly by splitting. A worm breaks into two or more pieces, and each piece regrows into a complete worm.
That sounds like it should make them easy to multiply, and under the right conditions a culture will grow. But the conditions have to stay right, and growth is slower than most people expect.
What Black Worms Need to Survive
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- Cool water: Black worms do best at roughly 55°F to 70°F. Warm water holds less oxygen and can wipe out a culture quickly. A thermometer helps you keep an eye on it.
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- Shallow water: A few inches of water in a wide container gives more surface area for oxygen than a deep tank.
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- Clean, dechlorinated water: Treat all water with a conditioner such as Seachem Prime. Chlorine and chloramine will kill worms just like they kill fish.
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- Low light: Black worms prefer dim conditions. Keep the culture out of direct sunlight.
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- Light feeding: Uneaten food rots fast and fouls the water. Overfeeding is one of the most common reasons cultures crash.
How to Set Up a Black Worm Culture
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- Choose a container. A shallow plastic tub or a 10-gallon aquarium works. Wide and shallow is better than tall and deep. Rinse it well with plain water, never soap.
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- Add a substrate. Black worms like something to burrow into. Hobbyists commonly use shredded unbleached paper towels, rinsed leaves, or a thin layer of clean sand. Keep it simple and easy to clean.
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- Add water. Fill with a few inches of dechlorinated water at room temperature or slightly cooler.
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- Add aeration. Run an air stone on low. You want gentle bubbles, not a strong current.
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- Add the starter worms. Buy live black worms from a fish store or online. Rinse them in clean, dechlorinated water first and remove any dead worms.
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- Keep it in a cool, dim spot. A basement or garage that stays cool works better than a warm room.
Feeding and Maintaining the Culture
Feed a very small amount of crushed
fish flakes or
sinking pellets every day or two. If food is still sitting there the next day, you fed too much.
Change a good portion of the water at least weekly, and more often if the water turns cloudy or starts to smell. Use dechlorinated water at about the same temperature. Remove dead worms and leftover food whenever you see them.
Healthy black worms are active, clump together, and quickly pull back when touched. If the worms turn pale, go limp, or the water smells bad, do a large water change right away.
Harvesting the Worms
Once the culture has grown, you can pick up clumps of worms with a
turkey baster or a
fine-mesh net. Rinse them in clean water before feeding them to your fish.
Only take a small portion at a time. If you harvest too many, the culture can’t keep up and will slowly die out.
What About Tubifex Worms?
Tubifex worms can be cultured in a similar way, but they’re harder to keep going. In nature they live in muddy, nutrient-rich sediment, often with slowly moving water, and that’s difficult to recreate cleanly at home.
The bigger concern is health. Tubifex often come from polluted waters and are more likely to carry parasites and harmful bacteria into your aquarium. If you do use them, buy from a reliable source and rinse them thoroughly. For most fish keepers, black worms are the safer choice.
My Honest Experience
I have tried this and all kinds of other ways, and I was never successful in producing enough to make it worth all the time and effort.
When you’re feeding a tank full of hungry fish, you need a lot of worms. A home culture can survive and grow, but getting it to produce enough to keep up with your fish is a different story. If you enjoy experimenting, go ahead and give it a try. Just don’t count on it as your main food supply.
The Easier Options
If you want the benefits of black worms without the work, there are two simpler ways to go:
Buy live black worms and keep them in the refrigerator. Put them in a shallow container with a small amount of cold, dechlorinated water and keep them in the fridge. Rinse them and change the water once or twice a day, and remove any dead worms. Kept this way, a portion of
live black worms can last for days or even a couple of weeks.
Use freeze-dried black worms. Freeze-dried black worms store easily, don’t need daily care, and carry far less risk of bringing disease into your tank. Most fish accept them readily. You can read more in my guide to the
benefits of freeze-dried black worms.
— Rick Mileski Sr.
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