They like flow but not a lot of flow and they are not dependant on lights. Treat em just like a feather duster. I have them in some of my PICO tanks and all of my larger tanks. While I like the common feather dusters, the cocoa worm seems a bit more durable if you have some rowdy hermits in the tank, and moving them is usually not a problem since they don't really attach to the bottom or rocks etc. The lfs here charges $22 to 25 for a cocoa worm....