I've noticed this with my dero worms! Now I'm curious why they're so attracted to the plant roots.
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Learning about Blackworms
- Thread starter RickyV
- Start date
prdad
Member
Root exudates? The same reason my Ottos are so chubby since I started growing Pothos and Monstera out of the top of the tank?
Something i have noticed when feeding sweet potato is the first 24 hrs they go mostly untouched. Then the 2nd 24 hrs they are mostly gone. A little later and they are completely consumed.
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The sweet potatoes are boiled for 15-20 minutes. I am currently feeding 400 grams per batch. When you subtract 77% water content you get 92 grams dry weight. They are going through this in about 2 days, so 92g / 2 days = 46g per day. Every 3g of feed = 1g of worm mass generated, so 46g feed / 3 = 15.33g of worms generated daily. Or 107g a week. This is of course assuming the sweet potato has the same feed conversion as whatever the commercial blackworm farms feed.
I currently pay about $1.05 USD per 453g of sweet potato. So about 0.0023 cents per gram of sweet potato. So 200g sweet potato per day/ 0.0023 = 0.46 cents per day. 0.46 cents / 15.33 g worms per day = 0.03 cents. So it costs me 3 cents to generate 1 gram of blackworms. Or about $30 USD to generate 1kg of blackworms. I bought them in bulk at 30 cents per gram so I am saving quite a bit of money growing them myself. I made a lot of assumptions/approximations in the calculations so it is not exact but I don't think it's too far from the actual numbers.
I am thinking of trying to just feed the 400g sweet potato per day rather than waiting the 2 days for them to consume them. So they always have 400g decomposed sweet potato to eat in 1 day and while they eat that the fresh 400g is decomposing to be ready the next day. Though this may generate way more blackworms than I can feed or even sell. If they were able to eat all 92g dry weight per day that would be 30.66 grams of blackworms generated per day. Or 214 grams per week. I could even scale up the feed per day and you could get some pretty crazy compounding.
0 Hrs
24 hrs later
48 hrs later
The sweet potatoes are boiled for 15-20 minutes. I am currently feeding 400 grams per batch. When you subtract 77% water content you get 92 grams dry weight. They are going through this in about 2 days, so 92g / 2 days = 46g per day. Every 3g of feed = 1g of worm mass generated, so 46g feed / 3 = 15.33g of worms generated daily. Or 107g a week. This is of course assuming the sweet potato has the same feed conversion as whatever the commercial blackworm farms feed.
I currently pay about $1.05 USD per 453g of sweet potato. So about 0.0023 cents per gram of sweet potato. So 200g sweet potato per day/ 0.0023 = 0.46 cents per day. 0.46 cents / 15.33 g worms per day = 0.03 cents. So it costs me 3 cents to generate 1 gram of blackworms. Or about $30 USD to generate 1kg of blackworms. I bought them in bulk at 30 cents per gram so I am saving quite a bit of money growing them myself. I made a lot of assumptions/approximations in the calculations so it is not exact but I don't think it's too far from the actual numbers.
I am thinking of trying to just feed the 400g sweet potato per day rather than waiting the 2 days for them to consume them. So they always have 400g decomposed sweet potato to eat in 1 day and while they eat that the fresh 400g is decomposing to be ready the next day. Though this may generate way more blackworms than I can feed or even sell. If they were able to eat all 92g dry weight per day that would be 30.66 grams of blackworms generated per day. Or 214 grams per week. I could even scale up the feed per day and you could get some pretty crazy compounding.
Your posts inspired me to try doing the same. I hadn't looked into black worms before, and to my surprise they are not readily available around here, I didn't find any for sale in the usual online marketplaces. But I got lucky and found someone nearby who had some and he gave me enough worms to start my culture.
I copied your idea and had it installed in a sump, slowly circulating water from the tank. My culture is growing very slowly, though, and I don't think I'll have any extras to actually feed the fishes for a while. I tried boiled sweet potatoes, but they rotted surprisingly fast, and started molding in 24h... I did have success with raw cucumber and blanched zucchini. I'm also giving them mulberry leaves (blanched and frozen), mostly because I have easy access to them and because the guy who gave me the worms said that he only had success when he stopped trying to feed the worms with food and started only giving them leaves (I don't know which plant he used).
Maybe when the culture grows a bit I'll try the sweet potatoes again.
I'm keeping them in a block of black foam, but that makes it even harder to determine if the culture is growing or not.
I copied your idea and had it installed in a sump, slowly circulating water from the tank. My culture is growing very slowly, though, and I don't think I'll have any extras to actually feed the fishes for a while. I tried boiled sweet potatoes, but they rotted surprisingly fast, and started molding in 24h... I did have success with raw cucumber and blanched zucchini. I'm also giving them mulberry leaves (blanched and frozen), mostly because I have easy access to them and because the guy who gave me the worms said that he only had success when he stopped trying to feed the worms with food and started only giving them leaves (I don't know which plant he used).
Maybe when the culture grows a bit I'll try the sweet potatoes again.
I'm keeping them in a block of black foam, but that makes it even harder to determine if the culture is growing or not.
I could be wrong but in my mind the molding was ideal. I believe it is the case for their terrestrial counterparts. When their food gets really decomposed they can really go through it fast. I choose sweet potato because of the high caloric density. I actually started fermenting some trout chow pellets before feeding it to them and they seem to really like it. But feeding these decomposing foods would require more flow/filtration.
Yes this is definitely a downside of using the foam, but I believe it has some use. With the amount I'm feeding they generate lots of waste so having something for them to grab onto helps me push some good flow through the culture without having so many leave it. I use the amount their eating to get an idea of their population. But also the amount of worms outside the foam, as once the foam gets full, the worms will be all over outside the foam.
I believe worms being outside the foam is a good indicator it is ready for harvesting. These are mine right now. I think the fermented trout chow really gets them to come out.
I tried setting up a smaller culture but again I found no increase in the weight despite them going through a lot of food. This leads me to believe the amount leaving these cultures is much more significant than I thought. I recommend adding some type of media bag at most 200 microns at your culture output to collect worms that leave. I recently set one up and I use it like a secondary culture. One of these bags with some type of frame can even be used as the actual culture. But then as soon as they get a tiny hole the worm losses will be significant, so I like using this just to catch worms that leave. They're essentially self harvesting this way as it is very easy to use a turkey baster to remove them from the bag.
prdad
Member
Only a small addition to the Blackworm thread. My latest discovery was dropping a clutch of Corydoras eggs into the tank and watching a couple of fungused unfertilised eggs get eaten but the healthy ones remained and hatched. I now could possibly have the fatest, fastest growing Corydoras when they get large enough to eat the Blackworms!
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Wigglers
Seedling
This is fantastic thread and has come just at the right time. I have introduced blackworm to my finned friends over a month aho and they really get stuck into them so i was looking fir info on culturing them. This has really given me plenty to go on . Thanks
Fishfur
Member
Incredibly useful information. I used to culture them a long time ago but never had results comparable to yours. I used granite pea gravel as a substrate back then. I can see I didn’t feed them nearly enough! I will have to try again armed with better info.
This is great to know! I usually use shrimplets for this, but blackworms would be much better since they live symbiotically with a whole bunch of other tiny microorganisms that can serve as early food.
One thing I should add to this thread is that if starting with tiny cultures it becomes much more important to keep worms from escaping your culture if using a flow through system. On my large culture losses to escapes are negligible compared to the total worms I produce. For example 1g of blackworms can turn into 500g in 9 months assuming a doubling time of about 1 month. But in the first month where you are only making 1g that month, loosing just 1g is enough to keep your one gram from never growing. The flow through system is more useful for larger cultures.
prdad
Member
The fry are certainly looking mighty chubby. And the blackworms are definitely helping clear up any baby brine shrip being left over.
I recently came across a method for culturing microfex/dero worms where the worms are kept in shallow water containers on a sponge. The worms live and feed on top of the sponge which is exposed to air. 
This method is supposed to be much more productive for culturing the dero worms, but I started to wonder if this would work for blackworms. I decided to try in on my worm powered infusoria reactor on my daphnia culture. I added the sponge and food on top, the blackworms and dero worms were soon all over the food on the sponge. I am still feeding mostly sweet potato but I also supplement with trout chow to give them a complete diet. My daphnia grown from this culture actually have orange guts from the sweet potato! I will need to take some pictures later to share.
I believe this same quantity of food being added directly to the water without the sponge would have caused a lot of worm deaths like I have experienced in the past. But no problems right now. Unfortunately I just had the sponge floating so the weight of the worms sank it, but the sponge still gives the worms very close proximity to the surface which I am beggining to believe may allow us to feed the worms more without destroying your water quality, or depleting the oxygen. Not sure if water quality of oxygen is the bigger factor here. But I keep moina in this worm culture and the worms would die much quicker than the Moina of I overfed.
I will experiment more with this method and see if the worms can be cultured with the sponge completely exposed to the air. Here is a video of the culture
This method is supposed to be much more productive for culturing the dero worms, but I started to wonder if this would work for blackworms. I decided to try in on my worm powered infusoria reactor on my daphnia culture. I added the sponge and food on top, the blackworms and dero worms were soon all over the food on the sponge. I am still feeding mostly sweet potato but I also supplement with trout chow to give them a complete diet. My daphnia grown from this culture actually have orange guts from the sweet potato! I will need to take some pictures later to share.
I believe this same quantity of food being added directly to the water without the sponge would have caused a lot of worm deaths like I have experienced in the past. But no problems right now. Unfortunately I just had the sponge floating so the weight of the worms sank it, but the sponge still gives the worms very close proximity to the surface which I am beggining to believe may allow us to feed the worms more without destroying your water quality, or depleting the oxygen. Not sure if water quality of oxygen is the bigger factor here. But I keep moina in this worm culture and the worms would die much quicker than the Moina of I overfed.
I will experiment more with this method and see if the worms can be cultured with the sponge completely exposed to the air. Here is a video of the culture
Fishfur
Member
I’ll be watching with interest to see how it goes.
