What fish was discovered in 2012 using a rock to open clams?

The fish documented using a rock to open clams is the orange-dotted tuskfish. Its scientific name is Choerodon anchorago, and it is a wrasse native to Indo-Pacific coral-reef habitats.

The behavior is a surprisingly elaborate feeding sequence. The fish first uncovers a buried bivalve by fanning or blowing away sand, then grips the clam in its mouth and carries it to a hard rock or coral surface. It repeatedly smashes the shell against that surface, using the rock as an anvil until the clam breaks open.

The footage was recorded in Palau in 2009 and described in a 2011 paper, with the journal issue appearing in 2012. That dating explains why trivia references often call it a 2012 discovery. It was widely described as the first video documentation of tool use in a fish, although related wrasses, including the blackspot tuskfish, had also been observed using hard surfaces to break shellfish.

The orange-dotted tuskfish is sometimes confused with the blackspot tuskfish because both belong to the genus Choerodon and show anvil-smashing behavior. For this specific filmed clam-opening report, orange-dotted tuskfish is the canonical answer.