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Big Bad Blackworm Tower – Culture Journal


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Recently, I was told there is a national blackworm shortage. So naturally, I saw this as a great opportunity to exploit the locals for that cash money.  ...er ...I mean as my moral duty to keep my local friends' fish healthy and fed. Yeah, that one. Time to figure out blackworm culture.

Wild Collection

A little research on blackworm habitats revealed they can be found in shallow water near the edges of marshes, swamps, and ponds with muddy sediment where they feed in decaying vegetation. Well ...there's a shallow, still creek with a mud bottom near my work. Not really a creek. More like a very long depression that stays filled with rainwater most of the year. 

I was hoping to find a private spot to collect because I don't like people coming around and asking me what I'm doing. NONE OF YOUR BUSINESS, OFFICER! Unfortunately, most of the creek is behind fenced private or state property except for one spot along the road where people like to dump their latest stolen car after stripping it for parts. That's what these spots are for after all.

I hadn't pulled over to look before my first collection trip a couple weeks ago so I wasn't sure if there'd be much life but wow it's everywhere. Judging by the amount of invertebrates I saw swimming around freely, it's doubtful there are any fish there which makes the spot even more ideal for something like this.

Now enjoy some pictures of the collection site:

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Shallow, mud bottom. Lots of decaying vegetarian but not enough to foul the water.

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Directly off the bank where the water level was higher a couple weeks ago.

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Grabbed a small wad of vegetation, found a blackworm first try. 

Separating from Debris

I took a 5 gallon bucket full home and dumped it into a 5 gallon tank. To clear up the water I put in a little USB pump with a sponge over the intake. Last time a few blackworms burrowed through the sponge so I'm pumping the water into a breeder net to catch the new baby pieces. 

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To collect the worms from the tank I made a plastic mesh cylinder filled with rocks. The first time I tried this most, if not all, of the blackworms climbed into the tower after 24 hours which made it easy to relocate them into a separate 10 gallon tank without the decaying veg that came with them.

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The tank sat for 3 or 4 days before this and was not aerated so they may have climbed the tower to reach the surface for oxygen or to escape the decaying plant matter. Or perhaps they were simply looking for a sweet bachelor condo where they can reproduce asexually and no one can hear them cry at night. It's hard to get the ladies when you're a worm.

Culture Tank

The blackworms are being kept in the same parameters of all my fish, 68-74°F, ~7.8 pH. Ramshorn snails, scuds, daphnia, cyclops, and newly hatched CPD fry (the container hanging in the front is a DIY fish egg hatchery) are being kept in the same bare bottom tank with a thin layer of detritus, an aquarium co-op coarse sponge filter, and a clamshell container filled with K1 biomedia.

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I made two more taller blackworm towers for the culture tank, one filled with lava rock and the other with pea gravel. The worms are showing a clear preference for the pea gravel so far which they populated a couple days after being put in the tank. I'm sure it's far less harsh on their soft, pathetic worm bodies. Soon I'll make a third with a mix of the two.

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I had the idea for the blackworm tower because most blackworm culture guides recommend keeping them in only a few inches of water of oxygen. Since the tank is a polyculture of multiple organisms and for water quality reasons I want the tank to be full to the top. If shallow water is necessary then these towers will give the blackworms a way to live closer to the surface. There seems to be an equal amount of worms living near the top and the bottom of the towers however. And for some reason a lot less around the middle.

The towers will also provide for much more space to populate other than just the bottom of the tank, make population growth easier to monitor, and the gravel will help with fragmentation. I haven't tested this yet but I'm also hoping the towers can be removed and rinsed over a bucket for easy harvesting.

(1)

Edited by modified lung
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Following, since I’m always looking for a better way to culture blackworms.  I don’t think I’m effective enough at fragmentation, so my cultures gradually dwindle as I feed out worms.  Plus I struggle to get them out of my gravel layer on the 2 culture tanks that still have gravel.

Edited by Odd Duck
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On 2/8/2022 at 7:09 PM, modified lung said:

@Torrey no professional writing here. Just hobby. Do you have a pic of your buffet? It sounds really cool 

I am rebuilding for the big tank, albeit very slowly. 

I absolutely will.post pictures (maybe even vids) as I build. Which is only being held up now, by my need to catch up from having had surgery... and covid.

Covid is really **exhausting**

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Biofloc Blackworms?

So far algae wafers seem to be the food my blackworms swarm on the most. I also read blackworms feed on bacteria. So maybe they will do well feeding on a biofloc culture. If you aren't familiar with this term, biofloc is basically an ecosystem of protein rich heterotrophic "bacterial biomass" and all the microorganisms it contains. It's a technique used by some shrimp and tilapia farms.

I start biofloc cultures by adding 1/8 tsp of molasses in 1 gal of water. Add an air stone and light and that's it. After about a week, masses of biofloc will grow big enough to start flaking off the side of the jar from the turbulence.

I use this method to culture crazy amounts of daphnia. But daphnia don't need a lot of oxygen and biofloc cultures consume a lot of it. And oxygen meters aren't cheap ...at least not as cheap as I am. So instead of culturing the biofloc and blackworms in the same container, I likely have to collect chunks of floc and drop them into the blackworm tank. We'll see how it goes.

Blackworm Tower Update

In other news, a friend stopped by to donate some blackworms he bought to the cause and the worms immediately contacted their real estate agents to get a piece of that prime condo action.

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Edited by modified lung
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Blackworm Tower Update, Reproduction? 

I've had the wild caught worms for 4 weeks now but the store bought worms, which were likely raised at the blackworm farm in Fresno, have only been in my tank for a week. But some reproduction might be happening already. The amount of worms in the tower is growing by quite a lot 

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Here's a view from the top of the back side which is even more populated.

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Also, small patches of worms outside the tower are increasing in number, like underneath this small patch of lava rock.

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...and under this bur from their collection site. They really like these burs for some reason.

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But it's hard to tell if it's really reproduction or just more worms gathering together from around the tank. After I took these photos I syphoned up most of the detritus on the bottom so I'll know worms aren't hiding under it out of sight. Then I'll take another picture next weekend.

Also, my CPD fry are loving it in the blackworm culture tank.

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Blackworm Tower Update

The population is definitely growing already. The sponge filter was clogged this morning and half of the worms were scattered across the bottom writhing. I took the opportunity to collect some of them and found a lot of small worms. All the original worms were 2-3x larger. A few hours after the aeration was fixed, all the worms moved back to the tower.

I would have expected more worms in the tower when aeration is low, not less. Maybe they don't climb the tower to get closer to the surface for oxygen. Maybe they are climbing it because it's easier to grab suspended particles to feed on? Although blackworms don't have the equipment to filter feed I'm told. Maybe they're feeding on bacteria inside the tower which benefit from the aeration or maybe without proper water movement the gravel becomes anoxic which drives out the worms?

These guys also shed a lot of detritus. The tank bottom was completely clean last weekend. Now there's a large buildup concentrated around the towers. I suppose that means they are feeding really well in the towers.

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Backside of the tower:

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I have to say, I'm surprised this is working out so well. My first ideas never work lol.

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Edited by modified lung
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@OnlyGenusCaps Do it! I would absolutely love to see other people's tweeks on the idea.

What I'm really looking forward to finding out months from now is if this can increase the amount of blackworms grown in a small space or if there's a max bioload before the need for water exchange becomes unreasonable. So far I've only replaced 1 gal of water every 2 weeks.

 

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On 2/20/2022 at 1:09 PM, modified lung said:

Do it! I would absolutely love to see other people's tweeks on the idea.

Well, it's not top on my list right now.  I've set out a rather ambitious schedule ahead of myself for the coming weeks.  But blackworms are top on my list of life fish snacks I want to culture.  So, at the very least I am following this closely with intent to try it.  Right now all I have enough of to spare is intent.  🤪 

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On 2/21/2022 at 5:31 PM, OnlyGenusCaps said:

Well, it's not top on my list right now.  I've set out a rather ambitious schedule ahead of myself for the coming weeks.  But blackworms are top on my list of life fish snacks I want to culture.  So, at the very least I am following this closely with intent to try it.  Right now all I have enough of to spare is intent.  🤪 

Indeed, I've been reading your journal. You've taken on quite the project. 

 

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  • 4 weeks later...
Posted (edited)

New Tower, New Design

Last week I made a new tower with an open center. This way I can shove food down the middle and shine a flashlight to see how they're eating. It's hard to get a picture inside there but here they are eating some zucchini:

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Normally there's a cap over the center opening to keep snails from raiding the blackworms for food. I added a 3:1 pea gravel, lava rock mix to this one. They are dense at the bottom because that's where the food is at the moment:

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A few days after adding the new tower, the worms almost completely abandoned the tower with 100% lava rock which isn't surprising. It might be too rough on them and I've noticed too much fragmentation at once will kill the worm. They've also almost completely left the tank bottom. They're still hanging out in the 100% pea gravel tower though.. Here they are swarming a frozen pea last week on top of that tower:

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Also a note on the drawbacks of wild collecting. You never know what else you might be coming for the ride (but I suppose the same is true of store bought). I noticed a worm freaking out and found this snail leech trying to eat it alive. I've removed two more since. 

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Here the tank parameters:

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Here's some pics of the new design without gravel. I originally made the center opening 1/2", which is the version pictured below, but have since replaced it with a ~1" center instead.

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(I'm getting the image rotate bug now too)

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Edited by modified lung
sweet typos
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On 2/20/2022 at 1:57 AM, Torrey said:

I wonder how many of the worms were from your towers, and how many of the worms were from your sponge filter.

Because my juvenile grow out tank is glass bottomed, no worm tower (because only floating plants), and the worms find homes in the sponge filter.

I recently started finding worms in my sponge filter in the culture tank, also.  Hard to harvest from there.

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Posted (edited)

@Odd Duck I previously had a sponge over the intake of a small pump in the tank. The worms kept digging into the sponge, get chopped up by the pump and deposited into a breeder net cage. Most of the sections were too small and would die off afterward.

I have a ACO nano sponge filter in the worm tank now. It's suspended about an inch over the bottom and as far as I've seen the worms can't get to it.

I had a large ACO sponge in a different tank. When I broke that tank down I found hundreds and hundreds of scuds living inside it. That's when I really started to like the coarse sponge filters.

Edited by modified lung
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Blackworm Biofloc

I finally cleaned out one of my biofloc jars and dropped the big clump of algae and bacterial growth that formed on the bottom into the blackworm tank. Holy horse knuckles, they have never swarmed any other food I've given them this much. Maybe 90% of them left the towers to get at it. Before this I've mostly been feeding vegetables, spirolina wafers, and the occasional flake food.

After seeing most of them in one place like this again, I think the population may have close to tripled since I started this a month and a half ago.

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