Fish Traps

[Stones]

If its crabs you want out of your tank, instead of using a pop bottle, just submerge a small drinking glass or a large shot glass into the substrate at an angle. Put some type of heavier bait in like a large piece of shrimp and leave it overnight. Crabs will crawl in to eat the shrimp but not be able to climb up the slick glass walls. If the crabs are small enough, the plastic tubes superglue comes in work pretty good.