In my view, wood is essential for Ancistrus species (common Bristlenose). It is thought that elements in bogwood, particularly lignin, may form an essential part of Bristlenose diet (according to Julian Dignall, owner of Planet Catfish). They are omnivorous, but primarily vegetarian. The very long gut is indicative of vegetarian fish. I would certainly have a couple chunks of bogwood in the tank. The lovely dark brown Malaysian Driftwood available in many stores is ideal because it often has tunnels and crevices, and you can provide an ideal environment for this fish. Their habitat whether flowing rivers or flooded forest is almost certain to be full of chunks of wood.
Byron.