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Grindal Worms

I love the grindals because they like normal room temperatures, unlike white worms that need it cool (I hate the idea of running even a small refrigerator just to keep it cool for the worms to feed the fish).  I grow them in small plastic boxes, as shallow as I can get (you're really growing them only on the top surface, so deeper boxes just take up more room without providing more worms).  I have a small rack (purchased with some little "drawers" from an office supply store, drawers discarded, that allows me to stack several in a small space) that holds several of them under the sink (they prefer the dark), and can stack more on top as needed, giving me enough growing surface to produce more grindals than all my fish can eat. 


Each box is filled with half an inch to an inch of Magic Worm Bedding (Magic Products Inc), kept quite moist.  I use this bedding for my worm compost bin, because it seems to keep the redworms happier, so I always have it on hand.  Other people use various soil or peat mixes, or go dirtless with sponges or green plastic scrubbies.  I trim the lids of the boxes off on two sides so they fit inset into the box, on top of the worms and their food, but cover most of the box.  The more of the surface you cover with the lid, the more of it you can actively use for harvest.  The edges of the lid that remain provide a convenient handle, and the plastic lid is easier and safer than the piece of glass that is often recommended:

view of lid

The boxes are loosely wrapped in a plastic bag to keep out fruit flies

worms in bag

Each evening I take off the lid,

worms on lid

return any visible pellets of catfood (like this in the middle of this closeup) to the box

worms on lid close up

and wipe the worms off into a dish of tap water:


The worms are swirled around and allowed to settle, the water poured off, and new water added, and rinsed this way several times while I'm also thawing the frozen food and preparing the brine shrimp and microworms.  By the time I'm done they are much cleaner and ready to be dropped into the tank from my miniature baster.  The box of worms gets a few fresh pellets of cat kibble.  I started with Science Diet feline maintainance light, since that's what I fed to the cat, but I have recently learned that kitten food may be better because it has more vitamin C that will eventually get passed through to the fish.  However, the Science Diet kitten food molded too easily, and the worms did not seem to swarm over it as readily, so I have switched to Purina Kitten Chow, which seems to work a little better.  Here is the fed culture ready to be covered, wrapped, and put away:


Alternative foods for grindals include trout chow, other fish food, baby cereal, or soaked slices of bread:  they're really not very picky.  But the kibble is clean, easy to use, keeps them up on the surface for easy harvest, and resists mold better than baby cereal.

All my fish love grindals, and I love getting a couple of tablespoons of live food daily from a bit of cat food and a small investment in space.  And I have not had to restart the cultures very often--they've gone about a year between restarts; if I add too much food and some molds (rare but it does happen), I remove the moldy bit and the culture goes on; if it gets a little too wet, a few days with the bag loosened dries it out a bit; if I leave on vacation I just let them go in their bags until I get back (refrigeration was a bad idea:  the worms died and it was nasty). 

I recently discovered what seems to be a really good way to start new cultures:  I take the cleaned, rinsed worms when I have some extra, pull them up in the baster, and let them sit in the baster until they sink into a sludge about to fall out of the tip.

dropper full o'worms

I put a few drops of this concentrated mass of worms over a fresh piece of kibble in a new container of fresh, damp, worm bedding.  There is a good ratio of worm to food right away, so the culture starts without a lot of moldy kibble or hungry worms trying to find their way to the new food.

Plastic shoeboxes are also popular to keep grindals, but beware that loose-fitting lids invite fruit flies.   Another unwelcome visitor to grindal and white worm cultures are springtails, tiny little bugs that look like little white specks on the surface of the culture media.  When they invaded my white worms (possibly coming from a bag of poor-quality peat I used for the bedding mix), they quickly took it over, despite attempts to flood and freeze the culture to kill them off (but spare the worms).  With the grindals, I found that they seemed to outcompete the springtails, without any special treatment.  I saw a few springtails, then a few more, then they gradually disappeared over a few weeks.

Grindals on scrubber pads

After an outbreak of mites in my grindals, which recurred after I subcultured them very carefully trying to avoid carrying along any worms, I tried some "soiless" cultures on green scrubber pads.  These are now going great guns and the mites have not entirely vanished, but are remaining at a low, manageable level.  I also switched from using plastic bags to an old pillow case to seal out the fruit flies, which also is working quite well.  These  cultures are much slower to get established, and respond to overfeeding with impressively nasty molds if you're too enthusiastic--daily feedings are best, just enough for the worms to eat within 24 hours.

Here is the stack o'cultures in the pillowcase:

pillow case

And what it looks like inside:


Baring the worms:

worms revealed

And this is what the culture looks about 8 hours after feeding:

fed culture

And the worms on the lid are ready for harvesting with a swipe of the finger:

worms on lid

The goop at the bottom may be where there are freshly hatched worms, so maybe it shouldn't be thrown out:


And you can make a little more of that by periodically rinsing the culture pad with a little tap water (not dechlorinated).

This is the dense, well-established culture:


And this is a new culture, only about 2-3 weeks old, given new blobs of worms and dampened kibble, little by little, only feeding as much as it will eat overnight.  It takes many weeks to build up to a well-established culture like the one above.

new cx

I have not been raising them on the pads for that long--about 18 months now--and don't have clear criteria for splitting or renewing cultures.  Gradually increasing the number of kibbles fed daily--again, only as much as the worms will eat--is a very slow but safe way to get them to the size and productivity of the very well established culture shown above.  

I think I got much faster establishment recently by a different technique, and I will try this again in the future.  The cultures are generally 3-5 pads thick, and when my best-established culture got overwatered, and started to smell of decaying worms, I removed a couple of the middle pads, rinsed them under the tap (gently, trying to remove some of the foul smelling muck but not let all the enmeshed worms escape), and switched it out with a clean pad from the just-started cultures.   All three cultures did well after this.

Overwatering is a problem with these cultures, as is drying out on hot dry days.  I generally add a little water to the bottom of the cultures daily after I harvest and feed them--just enough to keep the bottom quite wet and have a little water that will puddle if I tip the culture on end a bit, but not enough to immerse the entire bottom of the culture box in water.  If they do get overwatered and  a little moldy, pour out some of the excess from the bottom of the box.  Feed very sparingly, and give them time to come back.  They have come back amazingly well if I give them time.

White Worms

I gave up on these because my apartment was too warm for them (temps easily to 80 degrees in the summer even under the sink), and I could keep them going but never really thriving, whether I used synthetic sponges or dirt with ice packs in a cooler (and then I discovered grindals, which do thrive here).  Many people who keep them have cool basements or use a refrigerator or wine cooler set to about 55 degrees F.  Another alternative I just learned about from Jack Heller is to cut off the lower half of a 2 liter plastic soda bottle, fill it with water, and freeze it.  That block of ice, if placed in a standard styrofoam fish box, in the middle of a few inches of worm bedding, will take 2 days to thaw, at which point it can be replaced with a freshly frozen block of ice.  It gets too cold right next to the ice for the worms, so they hang out a few inches away from the ice block.  They're otherwise cultivated just like grindals, although some people grow these up on a much larger scale.  Some images of Charles' Harrison's white worms are here.  They are reputed to be fattening, so are not recommended as a daily dietary staple. 

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