Our silverfish clean bathroom grout. We keep them in a little matchbox, put the matchbox on the shower floor, open it up a crack, and turn out the lights. In the dark they scurry for the mold and residue of soap, which they digest as easily as binding glue. The next day, with the light, they return to their box, and you just need to move that box to a dry place. If you don’t let them feed every few days, then drop one of our food pellets into the matchbox.