Tiny fanged fish called blennies, which swim in the coral reefs of the Pacific Ocean, are armed with an unusual venom that could inspire new pain medications, British and Australian scientists said this week.

The venom of these fearless 1.5-three inch (four-seven centimeter) swimmers -- which are popular tropical aquarium fish -- numbs would-be predators, rather than causing them pain, said the report in the journal Current Biology.

"The fish injects other fish with opioid peptides that act like heroin or morphine, inhibiting pain rather than causing it," said Bryan Fry, an associate professor at the University of Queensland.

"The venom causes the bitten fish to become slower in movement and dizzy by acting on their opioid receptors."

Experiments using lab mice found the rodents showed no sign of pain once injected with the fish venom.

Fry said the venom is "chemically unique," and called the fang blennies "the most interesting fish I've ever studied."

Their behavior is also intriguing, he said, for the way they appear unafraid of predators and fight for territory with similar-sized fish.

Fry said the findings bolster the need to protect the Great Barrier Reef and other fragile ecosystems.

"If we lose the Great Barrier Reef, we will lose animals like the fang blenny and its unique venom that could be the source of the next blockbuster pain-killing drug," he said.