White worm culture. According to the internet these are Enchytraeus albidus. However, there are several different species and I'm no worm expert. This culture was started recently and you're likely to get a few other critters as well. You may find some red mites enjoying your food source as well as a tiny insect called springtails.

I have found the tiny insects to be well enjoyed by my guppies who love to feed at the surface anyhow. Yes live foods take some time to maintain and enjoy but I think you will see some great colors in your fish and more activity if you feed them to your fish.

White worms are small but the adults are a nice size for adult guppies or fish of similar size. You are also likely to be feeding juvenile worms to your fish. My white worms get leftover microworm food and they seem to enjoy it immensely.