1. (noun) marblefish, Aplodactylus arctidens - herbivorous fish, feeding on seaweed but they also eat the small invertebrates which live on the seaweed. They are active at twilight and during the day rest in crevices or amongst dense seaweed. The juvenile is silvery on the sides, blue grey dorsally, adults are green or brown with fine mottled lines of white, which gives a marbled appearance. Found around New Zealand coasts in depths down to 40m. Their length is between 40 and 60cm. This name is applied to an old fish of this species.