Some of the most powerful naturally occurring toxins known to humans are to be found in fish, the lethal fugu fish (pufferfish) a prime example. However, toxins have their uses too, and a new fish venom identified by researchers may hold out hope for the development of painkillers.

The venomous fang blenny is a small brightly colored fish that is found in the Pacific region, mostly among coral reefs, including the Great Barrier Reef along Australia’s east coast. As its name suggests, it has two large teeth on its lower jaw that release venom into the body of its victims. What is unusual is that the bite is entirely painless, because the venom contains opioids that act like an analgesic instead of causing pain.

The skeleton of a fang blenny, showing the two sharp teeth on the lower jaw. The University of Queensland

Bryan Fry, a researcher from the University of Queensland, Australia, said in a statement Thursday: “The fish injects other fish with opioid peptides that act like heroin or morphine, inhibiting pain rather than causing it. Its venom is chemically unique. The venom causes the bitten fish to become slower in movement and dizzy by acting on their opioid receptors. To put that into human terms, opioid peptides would be the last thing an elite Olympic swimmer would use as performance-enhancing substances. They would be more likely to drown than win gold.”

Fry, along with Nicholas Casewell of the Liverpool School of Tropical Medicine in the United Kingdom, led a team of researchers that published a study on various evolutionary characteristics of blenny fish. Researchers from Leiden University and the Leiden University Medical Center in the Netherlands; Monash University; and the Bangor and Anglia Ruskin universities in the U.K. were also involved in the study.

A striped poison fang blenny (Meiacanthus grammistes), Sept. 12, 2009.

Speaking of the potential medical applications of the venom, and linking it to the protection of the fish’s habitat, Fry said in the statement: “This study is an excellent example of why we need to protect nature. 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.”

Titled “The Evolution of Fangs, Venom, and Mimicry Systems in Blenny Fishes,” the study was published in the journal Current Biology.

Also known as poison-fang blennies or saber-tooth blennies, these fish belong to the genus Meiacanthus, and are frequently seen in aquariums.