This is the amusing moment a fish took a bite out of a scuba diver's rubber duck.

The ravenous Napoleon wrasse joined a group of swimmers exploring the coral reefs in Palau on August 21.

Footage shows the green sea creature moving behind one of the divers before lunging to chomp onto the mini turtle toy attached to his hat.

Upon realising it was not a real turtle, the fish spat it out while a frantic woman in the background could be heard gasping in shock.

The fish then slowly backed away, approaching another swimmer who was posing for a picture nearby.

The Napoleon wrasse is one of the largest reef fish in the world, capable of growing up to two meters long. Despite their size, they are generally gentle giants, feeding mainly on mollusks, crustaceans, and sometimes even toxic species like crown-of-thorns starfish.

Due to overfishing and habitat loss, the species is currently listed as endangered on the IUCN Red List.