the easter island butterflyfish is a bottom feeding fish. examination of its stomach contents have shown that it feeds on polycheaete worms, shrimps, fish eggs and barnacles, and fragments of the black sponge "amphimedon" sp. were also found. this was unexpected as butterfly fish are not known to feed on sponges, however the explanation may be that the sponge was ingested in error when the fish was feeding on the barnacles which had become entangled in the sponge.