Swimming Decorator crab

I have been feeding blackworms to fish for about fifty years and still do, but now I also raise white worms because I wanted something that I could "fill" with fish oil before I fed them to the fish. Here are some white worms. I put that piece of Matzo in there about 2 hours ago. in a couple of more hours it will be gone and it was covered in fish oil. I just take a knife and lift out a blob of worms from the top and no dirt comes along with it.
I also feed them Cheerios with fish oil.
All my paired fish are spawning and there has not been a disease in about 35 years. Must be something to it.