I did this as well, worst thing I could have done. These guys were green inside and out, it regular soil. I had to do water changes every day for a little over a week before I finally got it all out. Big mistake.
I always buy the regular night crawlers at walmart to feed my clown knives.
Now they are carrying some bait called wax worms.
I think they might be bee larva, but not sure. Has anyone used them to feed fish???