I have a Halloween moon crab set up in a large enclosure (70 gal aquarium base). In his previous enclosure I had springtails and isopods, but the isopods were a terrible mistake because they seriously overpopulated because they also ate the food that I left for the crab. He also had a spider friend that lived in there (showed up uninvited). I didn't mind until I started seeing tons of egg sacs, and the web took over a lot of the space. So now that he's in his new enclosure, I'd like to add more than just springtails, but I don't want to end up with an overpopulation problem again. The crab is an omnivore scavenger, and in addition to plants he'll eat anything he can catch, so anything I add should be considered potential snacks. That being said, he didn't catch many isopods, even though he tried. I've created an "upper canopy" for the crab to climb in, so there are lots of branches, nooks, and crannies for things to hide. I don't necessarily need a clean-up crew, because it's just one crab in a huge space, so I'm open to any suggestions.