I had a bunch, hundreds, around a year or so ago and found some info that they don't like higher flow. So I added some small power heads, 3 x800gph on a 60g tank. I also added a pair of blood shrimp from a tank breakdown at the same time. They were mostly gone in a month and completely gone in 3, didn't do anything different as far as food or maintenance. So either they hate flow, went through a cycle of sorts or blood shrimp eat them. Given how hard they are to eradicate in a tank even with things like flatworm exit which doesn't kill them all even at 10x dose,( it paralyzes them if I recall correctly) I think it was the shrimp.