They will slime off of any glue you try to use. Solutions: put them in a small dish with gravel/small rocks and netting over the top, once they attach to the gravel or rocks you can glue that in place; rubberband them loosely to the rock you want them on; wedge them in place with a small rock or netting till they attach. If you find they are unattaching themselves and floating around the tank it's because they don't like where they are so figure out why (too much flow or light, too little, etc.) and you'll have better luck. If they're just brand new to your tank try one of the other methods. Good luck!
