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Have you seen fish using tools?

Redmap Admin, 07 Feb 2023.

Scientists at Macquarie University are interested in your sightings of fish using rocks to open prey.

A fish using a rock as an anvil to open prey. Credit: Joseph Garcia

Have you seen fish using tools? 

Some fish use rocks and corals as anvils to crack open hard-shelled prey. Two scientists at Macquarie University are running a citizen science program on this behaviour and need your help.

Divers have reported that some fish can grab a prey item (typically an urchin or clam) and bash it rapidly and repeatedly onto a hard surface until it breaks. This is a case of tool use: The fish uses an external "object" to extend its physical capabilities and limit the oral damage caused by broken shells or spines.

Have you seen this behaviour during your snorkels, dives and at the aquarium? Please fill the participation form available at or send an email to Any information is helpful, so don't hesitate. 

Otherwise, open your eyes! You might see a fish using a rock as an anvil very soon. Try to identify and remember the species/gender/family of the fish when you see it.

Your participation would help identify all species of fish that use anvils in order to (1) find out if this behavior evolved one or more times in the evolutionary history of fish, and (2) test hypotheses about the evolution of tool use, such as whether tool use only evolves in species with large brains. Check the project website if you want to know more

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