Grindal worms - tips for strong yields?

[xZaiox]

Hi guys,

I've been breeding grindal worms for at least 1 year now so my fish get an occasional treat. I think I must be doing it very inefficiently though and I would love to get some advice on how to make it all work better. I currently have them set up in tubs with coco fibre as the substrate, and with holes drilled in the top of the tubs, covered with filter floss. Despite this floss blocking the entrance, somehow the cultures always get mites. I've tried putting the worms in a cup of water, leaving them for a bit and then using a pipette to pull only the worms out, since the mites supposedly float, but alas, somehow the mites always come back.

I'm currently feeding them dog food pellets. For some reason, production has drastically slowed over the last 3-4 months. I used to be able to feed my 180L tank 1-2 times a week, and now the fish are lucky to get worms once every few weeks. When the worms start trying to leave the tub, or when it smells, I replace the substrate with fresh coco fibre. I tried going soil-less with sponges but I found they bred much slower than with coco fibre.

I have a feeling the food I'm feeding them may be inappropriate, since I recently read that meats/fats/oils are less appropriate than grain due to going rancid easier. Anyway, although there is some info online, I feel that it's not very thorough. I would love to hear some advice from anyone who has had success breeding these little worms reliably. What did/didn't work?

 

[Fishfur]

The mites are most likely grain or flour mites & they almost always show up at some point. They appear to compete with the worms for food but not do harm to them. In fruit fly cultures they cause a lot of stress for the flies & cause a lot of problems, especially reduced productivity. Flies don’t breed as much with a lot of mites driving them crazy.

There are a couple of ways to help discourage them. One way involves using mite paper on the shelf or surface where the cultures are kept. The paper is impregnated with, if memory serves, one of the pyrethroids. Don’t know how available it might be these days. Any mites that crawl on it never make it to a culture.

I prefer to avoid pesticides wherever possible so another way is to keep cultures in a secondary container of some sort with DE (diatomaceous earth) spread thinly on the bottom where it does the same thing as mite paper but nontoxically. The DE abrades the exoskeletons of insects ‘n arthropods that walk on it and this causes them to dehydrate & die. It can help keep mite numbers low, maybe even nonexistent with a big helping of good luck.

Spreading a layer of rolled oats on the surface of an infested culture will attract the mites and the next day it should be possible to scoop/scrape them off with a large number of mites that are feeding on them.

Hope that helps a little.
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[Hanuman]

@xZaiox I would restart the culture from scratch with a known clean (not infected) culture.

Cocopeat has never been the most effective culture media IME. I use Scotch Bright pads. 3 layers of them with around half a cm of water sitting at the bottom. I pierce holes to the lid and add filter floss to prevent any insects ingressing. In 4 years I only had one culture box gone bad. It got infected with fly worms but I think that's because I left the box opened too long one day and I didn't noticed a fly had come in.
I feed them cheap carnivorous fish food which has a high protein content. I also give them old fish products once in a while to diversify. I spray water on top at each feeding. The way to increase population is to increase food volume and frequency but you need to do it progressively. Feed them every day and a little bit more every 2 or 3 days. You will start seing cocoons everywhere. Important thing is that food needs to disappear within 24h of feeding else you are overfeeding. Boxes and pads are rinsed weekly with tap water to remove any remains. You will inevitably lose some cocoons and worms but considering the exponential rate of reproduction it wont really matter. I then add back 400cc of RO water to each container. The whole thing takes me litteraly no more than 5 minutes.

Problem with cocopeat is that it progressively gets dirty and compacts and you can't clean it. These worms will reproduce very fast in a clean, aerated and moist enviroment, hence why I use Scotch Bright pads as they can be cleaned easily.

All these worms you see is just the tip of the iceberg. This is just 1h after adding the food. I am sure my cultures could be even bigger if my temperatures where lower. They sit at around 26C-28C. They reproduce better at around 20C-23C.

 

[Hanuman]

Dam I just realized the OP was from 2023. 😤
Oh well it might serve someone else.