i bought some a few days ago and can honest say they are brillient! they dig under my sand and venture out at night and early morning. they scavange around eating leftovers and blooodworms and look like a snake under water.my black kuhliis are often seen either under bogwood i have or next to thr bottom of the filter wher they push themselves as close as poss.
you can see little "pot holes" wher they have been digging and sometimes they will swim up and down the corners.great little buggers, they are.they dont creat much waste and end up eating fallen flakes/fish food so sort of lessen the bioload as the old food dont rot.(if that makes sence!?)