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How to Culture Blackworms (Black worms)

June 21, 2014 by Robert Brand 81 Comments

blackwormsLive blackworms rank among the best food that you can feed to your fish. Not only are they rich in protein and nutrients, but they can survive for an indefinite periods of time in a freshwater tank – which means that unlike other foods, they will never foul the water and will live until eaten by your fish.

I have personally kept black worms for nearly a decade now, and they remain my go to food for finicky fish. If you have a fish that won’t accept store bought food for one reason or another, then you should always start with offering them blackworms.

I originally started culturing blackworms because my rare (at the time) dwarf puffers weren’t accepting flake, or frozen food. After trying a few other foods that were all soundly rejected, I then moved on to trying blackworms – which were all hungrily devoured (along with the snails I offered shortly after).

One of the benefits to culturing blackworms is that they are one of the easiest live foods to culture. They are also hardier than many of the other live foods, and aren’t nearly as prone to large die offs as daphnia or adult brine shrimp.

Of course this hardiness comes with a downside, and they don’t reproduce as quickly as other commonly available live foods. A blackworm culture will be able to provide a few worms a day for harvesting – but anymore and you will quickly deplete the culture.

There is far from a consensus on the best way to breed blackworms, but it seems that the two methods discussed below result in both stable and prolific blackworm cultures.

Method 1 – Paper Towels

The method most commonly used for breeding blackworms is to use a shallow container filled with narrow strips of paper towels. While this is method is most commonly used in a laboratory setting, it also provides a reliable supply of blackworms for feeding to fish.

To start with, you will need a non toxic container that can hold at least 4 inches of water. Blackworms prefer shallow water, and will do best if they are kept in containers that hold between 4-6 inches of water. In the past I have used plastic sweater containers, or an old 5 gallon aquarium, but it doesn’t matter what you use, as long as won’t leach toxins into the water.

Any water used for a blackworm culture should be treated to remove any chlorine or chloramine and if you have access to it – spring water is often the best choice. Barring access to spring water, aged aquarium water also makes a good choice – as long as it’s from a well established aquarium.

After you have prepared the container and added water, it’s time to add the substrate. For this method you should use brown or organic paper towels. They should be torn into small strips, and added until they cover the entire bottom of the container. Some may have a tendency to float at first, but they should begin to sink after a short period of time.

Depending on the paper towels you use, they should last 10-14 days before they need to be replaced. You can add new strips of paper towels after a water change, and the key is to provide enough paper towels so that the bottom is fully covered.

The water in the container should be changed at least once every two weeks, but for optimal results, you should try to change the water every week. To change the water, simply take the container to a utility sink or toilet, and pour out most of the water – making sure not to lose any worms. Once it has been poured out, you can then add new water to top it up.

It’s also very important to remember that a blackworm culture needs aeration, and you should provide either an air stone or a small sponge filter. While a sponge filter will provide a far more stable culture, without an air stone the culture will likely experience slower growth.

Air stones provide two important functions for blackworm cultures. While its main function is to aerate the water, it also increases the number of worms that break up into pieces – which is how blackworms reproduce in captivity.

It’s extremely rare for blackworms to reproduce sexually in a culture, so the way that they reproduce is through fragmentation. The way that fragmentation works is that a blackworm breaks apart and each fragment grows into a new blackworm. If the fragment is missing a head or tail, they will simply regrow the missing part.

When an air stone is absent, fragmentation rates seem to slow down dramatically, and by extension the population growth. I have had some success using both a sponge filter and air stone, so this may be worth further experimentation to see if you can get the best of both worlds.

Feeding blackworms in this type of culture is extremely easy, and most of their food will be derived from the organisms that feed on the paper towels as they break down. They should be fed very sparingly and a few fish food flakes every few days should be more than enough. Make sure to never feed them until all the old food is gone, as you can easily foul the water if you’re not careful.

Method 2 – Gravel Substrate and Plants

While the paper towel method is an effective way to breed blackworms, it can also be very messy and you run the risk of losing worms during water changes. My preferred method for breeding blackworms is to use a combination of aquatic plants and gravel.

Like the paper towel method, you should choose a container or an aquarium that can hold at least four inches of water and any water that you use should be spring water or treated and aged aquarium water.

The main difference between these two methods, is that instead of paper towels for a substrate, you should use a very thin layer of gravel (only one piece thick) and add several plants. In my experience, this results in a far less messy culture, and tends to be more stable thanks to the plants.

For plants, I mainly use Java moss or water sprite, as both of these do well uprooted and also provide small amounts of infusoria for the blackworms to eat. You can try other plants, but most varieties of rooted plants won’t work in the shallow water provided.

Because there are no paper towels breaking down and feeding the small organisms in the container, you will have to provide additional food in this method. This can be a bit tricky, as the water can foul quite easily, but after a bit of trail and error (hopefully non-catastrophic), you will start to get the hang of it.

The best foods that I have found for this method are half medallions of zucchinis or spirulina pellets. Only use one pellet at a time and any zucchini should be removed after 24-48 hours or it will start to rot and ruin the water quality.

While this is purely anecdotal, I have had far higher population growth in this type of setup. While it may have something to do with the food, it more likely is the result of a greater number of worms fragmenting as they move through the gravel.

blackwormHarvesting

Harvesting blackworms is quite simple, and you can use either a pipette, or a turkey baster if you need a large number of worms. Anything else will likely damage the worms, and stay away from anything sharp or hard when harvesting worms.

Any worms harvested should be rinsed off before you put them in the tank, and try to avoid feeding too many worms at once to the fish. If you feed more worms than the fish can quickly eat, they may establish themselves in your tank, and there is nothing that ruins a show tank faster, than hundreds of little worms waving at the bottom.

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Filed Under: Articles Tagged With: blackworms, culturing

Reader Interactions

Comments

  1. sherell says

    January 7, 2015 at 4:20 am

    Thank you. Very informative, we are trying to breed them in a 1 footer, gravel java moss and water sprite, temp conditions werent mentioned, so its summer here in aust we have set them up outside for now.

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    • Robert Brand says

      January 7, 2015 at 5:00 pm

      I’ll add something about temp to the article in the near future, but most of the time they are happy with average room temperature. They are quite resilient outdoors though, but you do want to make sure that they don’t overheat – especially when they are kept in a small body of water like that. I would keep them in the shade and out of direct sunlight if possible. Something to be concerned about though, is if you keep them outside the culture will rapidly be invaded. I’m in Canada myself, so I’m not terribly familiar with the insects and other life there, but I know that here some seriously nasty – and dangerous things can invade a culture outside. I assume the same is true there too, so you’ll want to be careful with what you bring inside to feed your fish.

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  2. Jessica F says

    April 8, 2015 at 4:19 pm

    where do you purchase your initial stock of black worms? I’m having a hard time finding them online..

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    • Robert Brand says

      April 9, 2015 at 12:28 am

      They can be absolutely brutal to find sometimes. I’m lucky enough that a local fish store started stocking them a few years back. If you can’t find any fish stores that stock them, you should try local fish forums and see where people got them. Also, if you’re in the United States, aquabid.com is another good source of hard to find things like blackworms. Though I can’t vouch for the quality that you will receive.

      I hope this helps.

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  3. rick saathoff says

    May 16, 2015 at 6:33 pm

    you can order them from California black worms….. 559 291 0623
    Dan is the owner and says he sells about 1,000 lbs per week
    tell him rick s. from iowa sent you and he will charge double lol
    2.5 lbs are 69.99 with shipping included as of 5/16/2015
    he sells to well known institutions like john Hopkins for regerative studies on salamanders etc.

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    • Robert Brand says

      May 19, 2015 at 8:03 pm

      Thanks for the info Rick. It’s good to have a supplier on the page here.

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  4. Fluffy Luck says

    August 5, 2015 at 6:16 am

    I raised blackworms years ago to treat my freshwater fish, and I kept them in a plastic quart container with a lid – in my refrigerator. This is how I was told to keep/raise them by the LFS that sold them to me. I would swish the water around and pour off the top half or so several times every couple days or so, refilling with cold tap water after each pour. I would put a tiny pinch of flake fish food on top before snapping the lid back on & putting them back in the fridge. I couldn’t say how effective this was, but I always had a few for fish snacks! Some always ended up escaping into the gravel and seemed to reproduce there, but the fish would pick at them, so I never had an explosion of blackworms in any of my aquariums.

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    • Robert Brand says

      August 5, 2015 at 1:16 pm

      The fridge is perfect for keeping any that you want to feed to fish, but they generally won’t reproduce in there and most will only last a few weeks. They really need warmer temperatures to reproduce with any sort of reliability. How long did yours last in the fridge?

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  5. GreenGo says

    November 15, 2015 at 10:26 pm

    Could you substitute the gravel with sand? Would this (sand) work better or worse than the gravel you recommend? Also, what about the temperature of the culture? I’ve heard anywhere from mid-70s to mid-80s, but what do you think? Thank you, this is a very nice resource!

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    • Robert Brand says

      November 16, 2015 at 2:31 pm

      You should never use sand, since the blackworms would be able to burrow into it, and retrieval would be a nightmare for you. A very thin layer of gravel works much better, since they don’t have any where to hide when you go to pick a few of them out for your fish. Also, sand would probably get very messy during water changes, unless you’re using a full size aquarium.

      The best temperature I’ve found is low to mid 70s. Anything higher seems to have a detrimental effect on the worms, and anything lower their reproduction and eating really drops off. And I’m glad that you found this article useful.

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      • Fritz says

        January 10, 2020 at 12:38 pm

        At what density can blackworms be raised? If I were to feed and breed them, what can I expect per square foot of growing space?

        Many thanks,
        Fritz

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        • Robert Brand says

          January 13, 2020 at 2:44 am

          They grow incredibly slowly unless you have access to a protected pond outside. While they will grow very densely, they don’t reproduce quickly in a culture. Unless you have a huge setup, you’re probably only get a small amount weekly to feed to your fish.

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          • yann.H says

            April 2, 2020 at 11:12 pm

            Hello, I’m trying to culture black worms too… Quantity of worms don’t really grow… I’m doing several trials…
            Thanks Robert for sharing your experience.
            My question is: you talked about protected pond outside… Did you meant there is a method to breed same more intensively outside?
            I saw there is a worm farm in Australia, breeding huge quantity… but no information at all about their process… lol
            Thanks
            Yann.H

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          • Robert Brand says

            April 4, 2020 at 2:30 pm

            Honestly, I wish I could tell you the process. I’ve seen some blackworm farms,but I’m in the dark as to how they harvest and breed such large quantities. I know they usually breed in the shallow, long pools, with no fish or other wildlife in them. Some farms cover the ponds but most don’t. I’ll see if I can dig up some more information on the breeding process in ponds, and if I find any, maybe I’ll do another article.

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    • Jessa says

      December 2, 2020 at 3:23 pm

      I have a sand and river rock mix, and while it is messy “fishing” for worms, I am always overrunning with worms. I only feed them to my ADFs, so I harvest about 30 twice a day. My 1 oz starter culture is now 6- 10 gal tanks that I use as “currency” with local fish breeders. They are classified as “mudworms”, and I think they like the sand and river rocks set up over gravel.

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      • Robert Brand says

        December 3, 2020 at 2:13 pm

        The substrate recommendations are mainly based on ease of harvesting. While sand and mud both make work, harvesting the worms becomes a huge pain, especially in smaller setups.

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      • Bill says

        January 6, 2021 at 3:47 pm

        I also feed ADFs, I have been buying black worms every several months and keeping in the refrigerator and rinsing every day or two. I keep thinking about culturing them. I have plenty of extra tanks, it seems like it is pretty easy. Is there anything I should look out for?

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        • Robert Brand says

          January 8, 2021 at 2:00 pm

          Not really much beyond what’s in the article. They’re usually pretty easy to culture if you get fresh and lively worms. You can pretty much put them away somewhere and forget about them until it’s time to feed them or change the substrate.

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  6. Alex says

    January 31, 2016 at 5:10 am

    I have a 2.5 gallon aquarium with a lid will they be able to survive in the 2.5 without drowning? my LFS told me that they need extremely shallow water otherwise they drown. I also have a very small sponge filter do they need filters?

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    • Robert Brand says

      February 1, 2016 at 2:54 pm

      They won’t drown, as they absorb oxygen through their skin. However, they do best when kept in shallow water, since if the oxygen levels become too low, they can stick their tail up in the air and absorb more oxygen. But they can do well in water with low oxygen levels for extended periods of time, and if make sure to keep the water properly aerated, you won’t have any problem.

      Just from my own experience, I’ve seen worms colonize 55 gallon aquariums, and the water is very deep there. So while it’s best to keep the water to about 2-3 inches in a tank dedicated to them, they can thrive in just about any aquatic environment, as long as it is kept clean, and provides them with a food source.

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      • Alex says

        February 1, 2016 at 10:39 pm

        So a spongefilter will definitely be beneficial! Thank you Robert :).

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  7. Maj Carter says

    September 18, 2017 at 3:52 pm

    Thank you very much on the article very helpful for school

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    • Robert Brand says

      September 21, 2017 at 11:57 pm

      I’m glad it was helpful.

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  8. Stephen Fast says

    September 30, 2017 at 12:30 am

    Robert,
    This is very helpful. I have a couple of questions. First how many worms should I plan to culture per unit volume of water? Also I tried the zucchini though they floated and the worms never found them. The pellets sink, though foul the water as they disintegrate and thus are hard to remove. Any suggestions for a sinking vegetable or a way to sink the zucchini?

    Thanks,
    Steve

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    • Robert Brand says

      September 30, 2017 at 12:47 am

      Welcome to the glamorous world of culturing blackworms. I don’t have any exact measurements on how many worms to use, but keep the number relatively slow to start. I like to have them spread out, so they look pretty sparse on the substrate.

      As for the zucchinis, blanch them first and they tend to sink. Otherwise, when that doesn’t work, I use a stainless steal fork to hold it down in the water. It’s not attractive, but it’s effective. Also, if you’re having problems with the food fouling the tank, you could add a few snails to the culture. I used to culture pond snails with my blackworms. The snails were feed to my puffers and the blackworms went to the rest of the fish. The culture actually worked quite well for many years.

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    • Mary Capps says

      February 9, 2022 at 4:10 am

      Slice them thin, boil for a min and a half. Pull them out the boiling water and Throw in ice cold water and wait till they sink. They’ll sink in your tank. I do it for my fish. 🙂

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  9. JLu says

    October 5, 2017 at 2:41 am

    Rob,

    So I might have missed something, but in your second method do you still recommend using an airstone? Or do the live plants produce enough oxygen for the worms.

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    • Robert Brand says

      October 5, 2017 at 10:38 pm

      Ah…sorry. An airstone is very important. It helps to break up the worms to create new worms, since they probably won’t be reproducing asexually in there.

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      • Wendy says

        January 14, 2021 at 6:39 am

        How does air stone able to break the worms? Could you tell me more about this? Thank you

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        • Robert Brand says

          January 15, 2021 at 2:11 pm

          The worms are very delicate and the water turbulence from the air stone will often break the worms into two pieces. It’s not guaranteed by any means, but I’ve witnessed it happening to some of the culture at least.

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  10. Thomas says

    January 3, 2018 at 3:28 am

    I have a glass shelf container that’s 13 inches long, 3 inches wide, and 4 inches deep. A little more than half a gallon. I’m thinking of using the fine layer of gravel with some extremely easy plants like Brazilian pennywort, moss, and floating plants like frogbit. For food, I’m thinking of plant clippings, blanched zucchini/cucumber, and some ground up veggie pellets sparingly. I’m thinking of doing daily 50% (or more, depending on smell) water changes but no air stones or filter.

    I’m planning on adding a lot of plants and maybe some pond and ramshorn snails as I have a Paradise fish and two dojo loaches that will eat them. I’ll be attaching a very weak light to this container with the light on 24/7, or during the night. I’m hoping that the plants and daily water changes will be enough to compensate for the lack of aeration. I’ll manually cut the worms every now and then. What do you think of this set up?

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  11. Rico says

    April 9, 2018 at 7:24 pm

    Did you put a light fixture for your culture? I have mine in the basement, i was wondering if i should put lights.

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    • Robert Brand says

      April 12, 2018 at 10:38 pm

      I didn’t have a light on it, but it got non-direct natural lighting in the position. It seems to help grow food for them in the water, so I’d recommend some light. You don’t need anything fancy, though.

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  12. Joe Cooper says

    June 29, 2018 at 6:17 pm

    Robert,
    I have been told brown paper bags work just like paper towels or burlap bag material.

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    • Robert Brand says

      June 29, 2018 at 6:41 pm

      Maybe it depends on the bags, but I tried using paper bags in the past and they were a disaster. They bunched up and refused to break down, and I ended up losing the entire culture. You might have more luck than I did, but I stick with the tried-and-true now.

      If you go with bags, let me know how it works out for you.

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  13. Jessica says

    August 3, 2018 at 8:57 pm

    This was a great article! Extremely informative, thank you for that! Like you I am very lucky to have a lfs that keeps them in stock. Without black worms several of my fish would not have lasted. I have been curious though about culturing them myself. I was wondering if you have to use a recycled paper towel. So just using bounty won’t work?

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    • Robert Brand says

      August 4, 2018 at 1:40 pm

      The key is to use all natural paper towels. Many of the paper towels on the market use chemicals or dyes in the manufacture. And even the slightest contamination can be deadly to a blackworm culture. So, if you can find an all-natural paper towel, it would be fine to use in the culture.

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  14. bkgphoto says

    September 18, 2018 at 12:56 pm

    I am interested in giving this a try. Do you have pictures of your setup? How big are your cultures? I’d like to grow enough to supliment feeding of a 90 gallon reef tank and have them as the main food source for my picky eaters.

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    • Robert Brand says

      September 20, 2018 at 12:00 pm

      Unfortunately, I recently had my first child and my wife was terrified of my son getting a mouthful of blackworms, so it was strongly suggested I relocate them. I haven’t set up new cultures yet so I can’t give you a picture.

      However, I normally kept quite a few small ones going. I tried a couple of larger ones, but I found the volume of worms produced to be much less than the smaller cultures. I think it might be because there’s greater aeration in the smaller cultures, which causes the worms to break up and create newer worms faster. Also, if one culture goes belly up, it’s easy to start another one with worms from another healthy culture.

      I had four cultures going at one point in containers and small 2.5 gallon aquariums, which provided more worms than I could use for several aquariums. I was also growing pond snails in the same cultures to feed to dwarf puffers, and I think they helped to keep the cultures clean, because cultures I tried without worms often went bad. But that’s anecdotal at best.

      Let me know if you have any specific questions and I’ll try to help you out.

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  15. Joni Solis says

    November 12, 2018 at 1:01 am

    Your wrote, “If you feed more worms than the fish can quickly eat, they may establish themselves in your tank, and there is nothing that ruins a show tank faster, than hundreds of little worms waving at the bottom.” So my question is can the fish in the tank not catch and eat the black worms in the tank substrate? Are the worms too fast at drawing into the substrate that the fish can not grab them? Thanks.

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    • Robert Brand says

      November 12, 2018 at 1:20 pm

      The fish may pick off some of them, but usually the worms will hide in the substrate too quickly for the fish to get them. They’re quite adept at survival when they’re not out in the open and they will continually reproduce, usually replacing any losses they suffer.

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      • Joni Solis says

        November 12, 2018 at 5:04 pm

        Thank you for the fast reply to my question. Could they actually be good for a planted tank by eating stuff at the bottom and braking it down for the plants and making holes in the substrate around the plant roots?

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        • Robert Brand says

          November 14, 2018 at 12:25 pm

          They really aren’t strong enough to really aerate the substrate and they eat so little they will do little to eat much of the detritus in the tank. If you want something to fill those rolls, then Malaysian trumpet snails are your best bet – they eat missed food as well as digging through the substrate.

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          • Joni Solis says

            November 14, 2018 at 2:44 pm

            Thanks Robert. I was thinking about how they are native to the USA waterways. I worry about the Malaysian trumpet snails (and other no native snails) maybe getting loose and becoming invasive in local waters. I just found this with a google search, recommendations common to all aquatic invasive organisms for …
            https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprd3806222.pdf
            Distribution: Almost all US states except MT, ND and ME. … The clams also clog irrigation canals and drinking water pipes. …. Malaysian Trumpet Snail. 10 … Environmental Impact: This trumpet snail can out-compete native snails and alter …

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  16. agne says

    February 27, 2019 at 11:25 am

    can you feed them bloodworms? i have so many leftover but my dwarf puffers only eat live ones and unfortunately the ‘live’ bloodworms i bought from my LFS really was 10% live amongst dead bloodworms.

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    • Robert Brand says

      February 28, 2019 at 5:06 pm

      It doubtful they would consume the bloodworms but I’ve never tried to feed them anything like that before. I always culture snails will my blackworms though (I feed the snails to other fish like dwarf puffers) so if you add a few snails, then you could get rid of the bloodworms. But make sure you stick with small snails like pond snails or ramshorns snails.

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  17. Tiffany G says

    April 15, 2019 at 1:40 pm

    HI! I have a question, twice my blackworm culture disintegrated. I have them at work in 2.5 gallon plastic tank, about 4 inches of water and feed them vibrabites. They are fine for about 3 weeks and them boom…I come in and they are all disintegrated. Will high temperatures do that to them? They are in my office and it may get hot in there when I’m gone for the weekend. What else could cause this?

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    • Robert Brand says

      April 16, 2019 at 2:12 pm

      What sort of temperatures do you think it reaches during the weekend? But to be honest, it sounds more like a water quality problem. It’s really easy to feed blackworms too much and foul the water Also, what are you using for a substrate? And how often are you changing the water? I used to put very small snails and Java moss in some of my long term cultures to keep them going. The snails help to eat and uneaten food (and are also a food source for my other fish) and the Java moss filters the water.

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  18. Tiffany G says

    April 16, 2019 at 4:04 pm

    Hi and thanks for the quick reply. The water probably doesn’t get more than 78 degrees but I think you may be right, I would feed them every other day just to try and make sure they all got the food. I have gravel substrate with just enough to barely cover the bottom. It’s a small container so I may have put too much food in and maybe not doing the water changes enough. The water always seems to look clear so I was doing it maybe once a week or 10 days or so, should I do more? They didn’t look over crowded and I usually get 1/2 a portion. I will get some ramshorn and java moss then for my next try. I do have a hob filter do I need that or should I just use a air stone?

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  19. Rod says

    September 5, 2019 at 11:28 pm

    Thanks you for the above information Robert I’m about to start up a culture to feed my discus. Rod

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  20. Nelson Bowers says

    October 3, 2019 at 10:23 pm

    This is great information and easy to understand. Adding 8 (2.5″) discus this weekend to my 3 planted 40s, and now I know how to get going… I want them small, so I can raise them myself. It is a relief not to be a breeder anymore and I can’t think of anything freshwater with more personality than discus and angels. Two tanks with angels as well that will love the black worms. Down from 26 tanks to 5 planted/landscaped tanks and liking the hobby again.

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    • Robert Brand says

      October 17, 2019 at 3:21 pm

      Sorry the delay in getting to you (wife just had a baby) but I know the burnout from having too many tanks. For a while there my entire basement was tanks, as well as tanks in my office, living room, and kitchen. I’m never going back to that again, but by focusing on a few tanks, I’m having a lot of fun again. And

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  21. Shi says

    December 14, 2019 at 3:20 pm

    If I leave the worms in a reguar fish tank without fish, will they become a stable source of food for the fish within a reasonable amount of time?

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    • Robert Brand says

      December 19, 2019 at 11:55 pm

      They’ll never populate enough to become a sustainable food source for fish, unless you really understock the aquarium. They sometimes colonize an aquarium but most of the time their numbers are depleted quickly.

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  22. Ian says

    April 5, 2020 at 11:03 am

    Really informative article thank you.
    My question is about PH. What PH range do the black worms thrive In ?
    Regards Ian

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    • Robert Brand says

      April 20, 2020 at 1:19 pm

      They don’t do well in either basic of acidic water and should be kept in as close to neutral (7 pH) as possible.

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  23. wayne says

    October 18, 2020 at 2:30 am

    HI,

    Do these need light, or is dark preferred?

    Thank you!

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    • Robert Brand says

      October 29, 2020 at 1:00 pm

      They don’t need light and it sometimes help to keep them out of direct sunlight.

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  24. Lynette says

    October 26, 2020 at 3:05 am

    Hi Robert! Wow this is great info! Thank you for taking the time to share.

    I have a blackworm culture started and they are definitely thriving in my 1 later gravel tank with some live plants and an air stone.

    The problem I’m having is with the ammonia levels. I can’t seem to get them down to normal even after a water change with fresh spring water.

    Any ideas to decrease that ammonia?

    Also…this may be a silly question, but I assume you don’t have to condition spring water, correct?

    Thank you so much!

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    • Robert Brand says

      October 29, 2020 at 1:09 pm

      I’m really glad you enjoyed the article. Generally speaking, the ammonia comes from a new aquarium and may come from overfeeding. If you’re leaving food in the tank to decompose, it may spike the ammonia levels. If you continue having trouble with ammonia, I would consider adding a sponge filter. It should stabilize things within a few weeks if you do that.

      And spring water shouldn’t have any chlorine, so there’s no need to condition it.

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  25. Elle says

    January 22, 2021 at 6:07 pm

    I have a 36 gallon tank with 6 peas and 3 killis. I have a snail tank going and my husband won’t allow me to cultivate worms in the set up you explained above. Can I honestly buy some from LFS and just toss them in and hope the colonize? I have an air bubbler plus a waterfall filter. I bought a sponge filter but I haven’t decided to put it in yet.

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    • Robert Brand says

      January 23, 2021 at 2:35 pm

      If you place enough worms in the tank, they should colonize. But the population probably won’t be too high, and you’ll have to see worms waving at the bottom of the tank. Some people find that a little off-putting om their tank but if you don’t mind it, then go ahead.

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  26. Matthew says

    March 26, 2021 at 10:24 pm

    Last time I got these I believe they were from a scientific supply company. The instructions said to cut the worms up with a razor blade. I did this and multiplied my worms for each cut I made. They all seemed to survive and thrive in my tank. In fact I had a population explosion of them at one point. If you aren’t getting the reproduction rates you need you may want try this.

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  27. Kathy says

    September 12, 2021 at 12:21 am

    I found this very interesting and simply explained so it’s easy to follow. I just bought a small caecilian at a show. And he/she looks too small for the bait worms I was told to feed it. Unfortunately because of Labor Day, the LFS didn’t get their order of live blood or black worms this week. A while back, I had axolotls on a sand substrate and would occasionally treat them to live worms They did colonize the sand and I thought it was neat. They also used my moss balls as apartments. The axolotls did end up eating them all before I added more. They are very motion-triggered for feeding. I am motivated to intentionally culture them when the LFS gets the next batch in.

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  28. Kt says

    September 21, 2021 at 12:10 am

    Hey Robert (Hope I spelled it right),
    Could you possibly tell me how to get a air stone or a “sponge”? I really want to also know if the worms will go through a wire sieve that’s really fine? I hope this isn’t to much. Please and thank you!

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    • Robert Brand says

      September 21, 2021 at 11:42 pm

      Most pet stores sell air stones or filters. Though you’ll also have to buy a air pump to make it work. And generally speaking, they probably shouldn’t go through a very fine wire sieve. What were you thinking of the putting the wire sieve on?

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  29. Rosalind Porter says

    October 12, 2021 at 12:36 pm

    I am trying to breed blackworms because I thought it would be cheaper and practical.
    I have a small 20 liter tank half full, with a spongefilter and airstone. I have tried pea gravel where they hide very well, impossible to harvest even with a turkey baster.
    They are hard to collect in fine sand as well as the sand stays in the net.
    I have tried pieces of filter sponge which they like to climb into, the fish love this, but it only works if there is nowhere else to hide in the tank, so don‘t know if they would breed without a proper substrate.…..what would you suggest about harvesting?

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    • Robert Brand says

      October 13, 2021 at 11:10 pm

      For harvesting, there are two options. The first one is to leave an area with no substrate and the worms will tend to congregate there. The other option is to place a spirulina wafer or zucchini medallion in the tank. The worms should warm the food and will be easy to harvest then.

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      • Jesd says

        December 6, 2023 at 7:01 am

        I’ve found that by using a gravel/sand cleaning siphon at the bottom of my aquarium (where I let the colony live for my axolotls) and pumping into a 5 gallon bucket, after allowing the worms to cluster together in the bucket, I can dump out most of the water and harvest the bundle of worms with a turkey baster.

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  30. SGcvn69 says

    December 14, 2021 at 2:44 am

    How do you get rid of the leeches?

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    • Robert Brand says

      December 15, 2021 at 1:16 am

      I’ve only ever encountered a handful in the past. If you put your worms in the fridge for a short time, they should be relatively easy to pick out.

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    • Tiffany says

      December 15, 2021 at 3:06 am

      I just suck them up in a pipette and flush or throw away

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  31. Vince Picciolo says

    March 11, 2022 at 12:51 am

    Will blackworms be okay and survive in my freshwater aquarium when the water contains 1 TBS Aquarium Salt per every 5 Gallons of Water? I asked all my local pet shops and aquarium center, and no one could answer this question for me. If anyone knows, I would really appreciate the correct answer to this question. I’d like to start feeding my fish and my African Dwarf Frogs live blackworms , especially if they can survive a long time and live in the gravel. Thanks!

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    • Robert Brand says

      March 12, 2022 at 1:22 pm

      I’ve heard of them surviving at least for a while in a brackish tank, so a low-level amount of salt shouldn’t hurt them. But I haven’t been able to find any articles that directly relate to their survivability with salt in the water.

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  32. vikki says

    September 25, 2022 at 2:27 pm

    Hi Robert – hope life is treating you and your family well. I love that you wrote this in 2014 and still in 2022 this info is so helpful and available and we can leave comments here to support each other. I have a small blackworm culture I’ve kept in a 10″ round 4″ short plastic kitchen container. Has a layer of aquarium gravel maybe 1-2 stones deep and just an inch maybe 2 of water on top. The little cuties get some flake fish food every week or so after I drain off most of the water and replace it with water from one of my tanks. There’s a few snails in there too. When I want to feed, I shake the container and the worms wriggle up to the surface where I can easily suck them up with a medicine dropper. I suppose the shaking also breaks them up a bit for reproduction. Been doing well for 11 months straight now from a small group I bought at LFS. Have just enough to feed a treat to 75g community tank once a week. While at a fish show this weekend, I bought the smallest bag available from a vendor. WAY too many oh my gosh. I cleaned them and pulled about 20 leeches as I moved them into my too-tiny-for-them set up late last night as a temporary hold while I find new containers. Got up this am to check on them and they’ve chosen to explore and see if there is a less crowded area to live on my counter ha ha. These and scuds are my favorite live foods for ease and consistency. Excited to have such a large batch to start a few colonies.

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    • Robert Brand says

      September 26, 2022 at 1:22 pm

      I’m glad to hear all this information is still helping people out. And it sounds like you’re off to a good start—aside from the explorers. Good luck starting your food colonies.

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      • Lynmichelle Lenney-Koeberle says

        March 15, 2023 at 8:55 pm

        I have black worms established in my 46 gallon tank. However, all I have now are the tiny baby worm globules growing. They are growing very very slowly—like months. When I clean my tank I remove them to another place with aeration, plants, natural paper towels and a small amount of food. The temperature is in the 60’s usually during winter. Do I need something in addition? I don’t see them thriving after I move them from the aquarium.

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  33. Matt says

    April 20, 2023 at 12:42 am

    Hi great writeup thanks!
    I have a question on feeding. I just started my culture today and they seem all healthy, about 4″ water with a sponge filter/aireator.

    I tossed a sinking algae wafer in there and they seem to be ignoring it. Do they take time to start eating after stress of shipping or are they actually picky?

    Thanks!

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Trackbacks

  1. What Do Clownfish Eat In An Aquarium - 3 Good Healthy Food! says:
    October 10, 2022 at 10:47 am

    […] Blackworms are another excellent live-feeding alternative for your clownfish. You may either cultivate your own blackworms or buy them online and preserve them in the fridge. Clownfish also eat amphipods and copepods. Mysis or brine shrimp are also popular live food sources for clownfish breeding. […]

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  2. How Long Do Worms Live In Dog Poop? – BabelBark says:
    October 10, 2022 at 10:59 am

    […] with the tail resembling that of a fish. Adults are classified into three types: brown worms, black worms, and white […]

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  3. Black Worms In Aquarium - Betta Care Fish Guide says:
    October 31, 2022 at 3:27 pm

    […] photoperiod of 14-16 hours of light and 8-10 hours of dark is ideal to culture blackworms. Blackworms require flake or sinking fish food to be fed to them on a daily or weekly basis for […]

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