It's a simple tank with just gravel and a driftwood that doesn't have many nooks and crannies for them to hide in and some stem plants. Water wisteria, Ludwigia Repens and one Java Fern. There isn't that many hiding places for every single RCS to just completely disappear.
My gravel is white to make my RCS stand out, and I haven't seen a single speck of red.
My betta went on a feeding frenzy when I originally introduced the RCS but he left enough to repopulate themselves. He's not even looked at one since. The RCS has been with him for about three months.