A diverse array of animals has evolved the ability to use tools (e.g., primates, parrots, octopus, crabs, and wasps), but the factors leading to tool use evolution are poorly understood. Fishes could provide insight into these factors via comparison of differences between tool-using and non-tool-using species. Anvil use is one example of tool use by fish: the fish holds a hard-shelled prey item in its mouth and strikes it onto a hard surface (anvil) to open it. Through a community science program called Fish Tool Use, marine biologists collected 16 new observations of anvil use in five species of a group of wrasses (colorful reef fish) called the New World Halichoeres. These new observations provide the first evidence of anvil use by Halichoeres brasiliensis, Halichoeres poeyi and Halichoeres radiatus, and the first video evidence of anvil use by Halichoeres garnoti and Halichoeres bivittatus.

Tool use was once thought to be a uniquely human trait and play a fundamental role in human evolution.

Evidence now suggests that tool use is widespread among animals.

An animal is using a tool when it uses an external object to accomplish a particular task, such as when some capuchin monkeys use stones to crack open nuts.

Using a tool allows the animal to achieve the task or do so more easily. Tool use appears to be highly beneficial to animals, raising the question of why all animals do not use tools.

The study of the evolution of tool use to date has been limited by the difficulty in finding closely-related populations or species with varying degrees of tool use and contrasting morphology and ecology.

Though poorly studied, tool use in fish could be an exception as fish is the most specious vertebrate group with high ecological and morphological diversity, sometimes even between closely-related species.

Anvil use is one example of tool use in fish. When using an anvil, a fish will (i) grab a hard-shelled prey item such as an urchin or a bivalve in its mouth, (ii) swim to a hard surface such as a rock or coral head, and (iii) strike the prey item quickly and repeatedly on the hard surface until it breaks open.

Anvil use has been described in 26 fish species, all wrasses belonging to the family Labridae.

“Tool use is typically associated with humans, but this behavior is proof that fish are far cleverer than they get credit for,” said lead author Dr. Juliette Tariel-Adam, a researcher at Macquarie University.

Through a citizen science initiative Fish Tool Use, Dr. Tariel-Adam and her colleagues gathered 16 new observations across five species of Halichoeres wrasses.

The findings mark the first evidence of anvil use for three species and the first video evidence for the other two, and extend the known range of anvil use to the western Atlantic.

“With these newly discovered tool-using species, it becomes clear that many species of wrasses use tools that we previously didn’t know about,” Dr. Tariel-Adam said.

“The study adds to research into fish intelligence,” added senior author Professor Culum Brown, also of Macquarie University.

“They demonstrate flexible and dexterous tool use, expanding our understanding of tool use evolution in the animal kingdom.”

The team’s results appear in the journal Coral Reefs.

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J. Tariel-Adam et al. Tool use by New World Halichoeres wrasses. Coral Reefs, published online March 26, 2025; doi: 10.1007/s00338-025-02633-w