This works great for MTS (Malaysian Trumpet Snails) or Planaria and any other bugs that love to hang out in the gravel... not that MTS are bugs but they can overrun a tank pretty quick if you feed too much. It is completely fish and shrimp safe (especially bugs in a shrimp tank are hard to remove without catching some baby shrimp) and I have heard horror stories of other traps trapping fish and them dying.
All you need is a cleaned bottle (I just use a water bottle) - Slice off the top and the bottom and chuck the middle in the bin unless you are into plastic bracelets. Remove the lid from the top half... this is where the critters are going to crawl in..
After just 15 minutes a lot were already trapped
Malaysian Trumpet Snails crawling via the bottle neck into the trap
Happy hunting and let me know how it works for you xxx