I start all of my fry off on freshly hatched BBS and microworms. However, I do not like to rely too much on microworms due to issues with ventral fin development, and I find the daily ritual of hatching and harvesting BBS to be something of a hassle.
This is where grindal worms come into their own.
I culture soil-less grindal worms, and I have found them to be extremely low maintenance in terms of care and harvesting.
This is all I use to culture soil-less grindal worms:
To set up a culture, all I do is take two kitchen scourers and place them one on top of the other in the plastic container. I then add enough water until the bottom scourer is completely covered but only the bottom part of the top scourer is wet.
Then basically all you have to do is put your starter culture onto the top pad and you're done.
Instead of poking air holes into the lid, I like to cut a small rectangle out of the plastic, and cover it with a coffee filter. I find this not only provides more ventilation for the worms, but also prevents anything from getting into your culture (I had a big problem with insects in the past).
If I notice that the water is getting too low, I simply top it up. I feed my grindal worm cultures two-three pieces of dried cat food every day. I find that feeding them regularly is best if you are heavily harvesting from your cultures.
I know some people use things like glass or craft mesh to harvest their grindal worms. Personally, I use either a pair of long tweezers to get worms off the scourer, or my finger if the worms are on the sides of the container.
I try and transition my fry over to grindal worms as soon as possible as I think they give me a better growth rate than microworms or BBS.
Grindal worms do not survive indefinitely under water, so do not feed to excess as they can foul the water.
I find grindal worms make an ideal transitional food for fry that are getting too old for BBS, but are not yet big enough to take white worms or blackworms.
Hailing from Melbourne, Australia, I currently keep and breed a number of species from the coccina complex.