I mentioned culturing blackworms back in May, but never followed up on a question from Bob Bock...
I got 2 smallish "portions" of blackworms from a local fish store sometime mid-winter. I've been maintaining them ever since. During a period when I was feeding regularly and measuring the growth (by volume), I was getting doubling rates of roughly once per 3-4 weeks.
I have the worms in a under-bed sweater box, with a standard box filter hanging on the side. I've got about 1/2 inch of very clean (rinsed many times) play sand in the bottom. After a couple days, the worms will all be buried into the sand, except when actively feeding.
Total depth of the water is about 3-4 inches (about 5 gallons total). Sometimes I run an airstone, but I bet the filter takes care of aeration just fine. The worms really go for spirulina tablets, and seem to be okay with a soy pasta I've given them (terrible-tasting relic of the "low-carb" craze -- was $0.01/package on clearance at a local bulk food store).
I've gone a month or more at times with no water change, even when actively feeding. When I do change water, I use my fingers to thoroughly turn over the sand and dislodge all the worms, then use my hands to create a whirlpool in the tub. The worms clump on the surface in the center, and I can carefully pour all the water off. I re-fill and repeat this a couple times to clean. Seems to work well, with only a few worms lost in the pouring process.
At first I thought I needed to keep the worms in the dark, but it doesn't seem to make any difference. They feed regardless of light level. There's some cyclical nature to their feeding, but I haven't figure out what.
I've focused only on growth of the colony, with almost no harvesting. You'd need a really big area devoted to it if you were going to use the worms as a staple food. Harvesting would be really simple, using the same "whirlpool" method for cleaning. I can pick up big clumps of pure worms with my fingers, due to the fact that they ball up when disturbed.
It took a couple weeks after getting them from the store for them to really settle down and start eating. When they divide, the "tail" end takes something like a week or more to grow mouthparts. Fresh from the store, it seemed like there was a fair bit of necropsy at the ends, so I'm guessing the mouthparts were in bad shape.
I recently moved, and one of my two cultures died very suddenly as I was setting them up in my new place. All worms were dead and bleached white in the span of an hour. No idea what did them in -- water (chloramine?), some residue on filters, whatever. At least the larger culture made it through with only maybe 1/4 loss after a week in a small container in the fridge (and a few water changes).
Hope this is useful to someone. Again, unless you're going to devote a lot of space, I think you're only going to be able to feed as snacks. Since reproduction is *only* through division, rate is really limited. The huge outdoor ponds that the California raisers use are the way to go for bulk production -- and prices for bulk quantities are pretty reasonable.
Lewiston, Maine (on the Androscoggin River)
Date: Mon, 22 May 2006 08:06:00 -0500 (CDT)
From: Bob Bock <bockhouse1-in-verizon.net>
Subject: NANFA-L-- blackworm culture was Feeding suckers and other benthic feeders
Hey, Jase, how do you culture your blackworms?
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