Several species of wrasses have been observed using rocks as anvils to crack bivalve (scallops, urchins and clams) shells. It was first filmed [18] in an orange-dotted tuskfish (Choerodon anchorago) in 2009 by Giacomo Bernardi. The fish fans sand to unearth the bivalve, takes it into its mouth, swims several metres to a rock which it uses as an anvil by smashing the mollusc apart with sideward thrashes of the head. This behaviour has been recorded in a blackspot tuskfish (Choerodon schoenleinii) on Australia's Great Barrier Reef, yellowhead wrasse (Halichoeres garnoti) in Florida and a six-bar wrasse (Thalassoma hardwicke) in an aquarium setting. These species are at opposite ends of the phylogenetic tree in this family, so this behaviour may be a deep-seated trait in all wrasses.[115]
It has been reported that freshwater stingrays use water as a tool by manipulating their bodies to direct a flow of water and extract food trapped amongst plants.[116]
Prior to laying their eggs on a vertical rock face, male and female whitetail major damselfish clean the site by sand-blasting it. The fish pick up sand in their mouths and spit it against the rock face. Then they fan the area with their fins. Finally they remove the sand grains that remain stuck to the rock face by picking them off with their mouths.[117]
Banded acara, (Bujurquina vittata), South American cichlids, lays their eggs on a loose leaf. The male and female of a mating pair often “test” leaves before spawning: they pull and lift and turn candidate leaves, possibly trying to select leaves that are easy to move. After spawning, both parents guard the eggs. When disturbed, the parent acara often seize one end of the egg-carrying leaf in their mouth and drag it to deeper and safer locations.[118]
Archerfish are found in the tropical mangrove swamps of India and Australasia. They approach the surface, take aim at insects that sit on plants above the surface, squirt a jet of water at them, and grab them after the insects have been knocked off into the water. The jet of water is formed by the action of the tongue, which presses against a groove in the roof of the mouth. Some archerfish can hit insects up to 1.5 m above the water surface. They use more water, which gives more force to the impact, when aiming at larger prey.
Triggerfish (Pseudobalistes fuscus) blow water to turn sea urchins over and expose their more vulnerable ventral side.
