GRINDAL WORMS: How to raise and collect them to feed to bettas and betta fry.

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A common interim live food until the fish get large enough for adult brine shrimp or blackworms are grindal worms. These worms are ten to twenty times the size of vinegar eels and microworms, white, and live in moist peat. They eat Gerber dry baby food mixed with water and prefer cool dark conditions. I purchase some from The Bug Farm to experiment with culturing them and to see how well the fry accepted them as food.

The worms arrived in a 1-quart plastic bag with one-cup of moist peat. The worms could be seen clinging to the sides of the bag. I dumped the contents into a tupperware container, used a light spray of water to wash out the worms clinging to the insides of the bag, added two hand-fulls of moist peat on top of them and placed one-tablespoon of wetted baby food in the center of the peat. The box was partially covered and placed in a cool dark closet. Twenty-four hours later I counted several dozen worms nibbling at the edges of the food. Twelve hours after that there had to have been hundreds of worms attacking the food. After another twelve hours (for a total of 2 days) all the food was gone. The worms lay in a layer over the area where the food had been.

I was surprised that the instructions for culturing Grindal worms recommended using peat moss because it is extremely acidic. Another site with culturing instructions comments on this and recommends the use of a peat-based potting soil. I added an inch-deep layer of potting soil over the pure peat layer I started the worms in. After two days, I saw twice as many worms in the potting soil layer as in the peat.

 I've been feeding the worms by dropping a pinch or two of Gerber flaked baby food in a pile and wetting it with an eyedropper. I've noticed a problem with this technique in that it creates a solid wet glob of food that can only be reached by very few worms. I started spreading the food around in a very thin layer so that as many worms as possible can get to it and they seem to prefer the change.

It's almost impossible to make estimates of how fast the culture is growing but I get the impression that the number of worms has doubled in only one week. If true, this is an astounding rate of increase. So far they are extremely easy to raise and harvest and give off no noticeable odor. Both my five-week old fry and adult bettas eat them enthusiastically.

NEW!!! Lifetime in water test results: I dumped several Grindal worms in a jar filled with tank water and checked back every day to see how they were doing. After five days I released them because they showed no signs of distress and appeared capable of going on forever.


Product Disappointment:

I've purchased many products from The Bug Farm and in general been satisfied. However, I recently ordered a 1/2 pound jar of the Grindal Worm culture. This is a mixture of Grindal worms in growing a growing medium. It comes complete with a collecting glass and a small packet of food. It's advertised as enabling the purchaser to immediately begin collecting Grindal worms and feed them to his or her fish. I found this to be a gross misrepresentation. There were so few worms in the medium I received that if I collected them all they'd hardly fill a single four-week old betta. Worse still, the density of worms was so low that after four days of trying to coax them to the surface, there still wasn't enough to hardly see. To add insult to injury, the medium was heavily infested with fly maggots.

The Bug Farm is an invaluable resource for live foods. I will continue to use them. However, I cannot recommend their medium (1/2 pound) Grindal worm cultures.


Grindal worm collection breakthrough! As easy as Grindal worms are to raise, there is one aspect of collecting them that is annoying: dirt from the growing medium tends to contaminate worms collected for feeding to fish. Many times there is so much dirt that it's impossible to locate enough clean worms to feed to the fry. Here's a trick that makes it easy to collect clean worms:

Sprinkle one side of a clean glass plate (In my case, 6 x 8 inches.) with worm food, wet it with a spritzer, and place it food side down on top of the growing medium. Let the worms eat it all off and repeat one or two more times. This ensures that there are a lot of worms right on the surface for collection. These conditioning feedings only have to be done one time and can be skipped if the worms are already swarming on the top of the medium. Next, set up the glass plate as before for feeding them, but this time use a short piece of dowel to lift one end of the plate off the growing medium. The worms will start feeding at the end in contact with the dirt and slowly work their way up the glass. As they do, they form a straight line of worms that's 1/4 - 1/2 inch thick. When you want to collect worms for feeding to fry, simply lift the glass and pick up as many worms from the line as needed. The clump of worms should be clean and free of dirt.

The white area on the top half of the glass plate is the food that the worms haven't eaten yet. The beige band in the middle is the line of worms. They stand on each other to reach the food. The clean area below the worms is the area they've cleaned of food.

Lifting the glass plate exposes the worms in a dense clean line 1/4 to 1/2 inch thick and wide. I'm scooping them up here with a plastic paddle but have learned that a tweezers used with a gentle touch works better. This technique produces worms that are easier to collect than scrapping them off the bottom of the glass plate and they are much cleaner.




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