This situation is placing increasing pressure on Caribbean coral reefs, which are already plaqued by climate change, disease, hurricance, pollution and overfishing.

One solution is to restore the threatened staghorn coral, which the small threespot damselfish favour as locations to grow algae to use for feeding and nests for breeding. The staghorn coral is preferred for their long, thin branches, which serve as ideal hiding places.

Fossil records show that threespot damselfish commonly exploited staghorn coral on Caribbean reefs for at least the last 125,000 years. Until the 1980s, this coral was the most common coral there - then disease, hurricane and other environmental assaults started to take their toil. Today, the staghorn coral is listed as threatened, under the US Endangered Species Act.

"Once staghorn coral disappeared, the fierce little beasts switched to killing slow-growing coral heads," said Les Kaufman, fish biologist at Boston University and Conservation International.

Coral heads are less desirable for damselfish because they have fewer hiding places. Unlike staghorn coral, head-corals cannot recover quickly enough to keep pace with the death-bites of damselfish, so the coral heads could take hundreds of years to recover.

"Threespot damselfish are now killing slow-growing coral heads, much more so than before and regardless of how many predators are around. We strongly advocate conserving fish stocks, but in this case restoring the staghorn populations will be far more effective in fixing the damage," said Rich Aronson, coral reef ecologist at Florida Institute of Technology.