Tropical Fish With Venomous Bite Could Provide New Painkillers

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The fierce-looking fang blenny, also known as the poison-fang blenny or the sabre-tooth blenny, fends off predators and competitors by injecting them with a heroin-like substance that impairs them rather than kills them. That their famed fangs contain venom they use against animals that try to eat them has always been known.

This made the fang blenny a curiosity; the scientists knew it to be venomous, but set out to understand how and why its bite was painless.

Snakes, scorpions and spiders are the usual suspects for this kind of research, but with so many venomous fish out there, we could find some useful chemicals in them, too.

Bryan Fry, from the University of Queensland, explained that fish with venomous spines on their bodies "produce immediate and blinding pain". Unlike most venomous creatures, blennies don't use this venom for capturing prey - they use it to escape their predators by getting them high.

"The predators would shake and quiver, and open their jaws and gills really wide", says Nick Casewell of the Liverpool School of Tropical Medicine, UK, and joint leader of a team that has established the ingredients of blenny venom.

The effect of the aquarium fish's venom shows potentials in the development of a new class of powerful painkillers. They started by imagining the small jaws of this tropical fish collected from the Indian and Pacific Oceans' area to reveal that not all the members of this species feature venom glands at the base of their canines. The fish were then returned to the tanks and the swabs were suspended in a solution to draw out the venom.

Researchers found that the fang blenny, a reef-dwelling fish, administers a bite that is laced with opioids.

Fry: Defensive venoms, whether those in cobras or in stingrays, are well known for their extreme pain-inducing action. He believes this suggests that "fang blennies first evolved large teeth, which certain species then coupled with venom". Recently, as Popular Science's Mark D. Kaufman reports, researchers learned that the fish spends much more time on land than previously thought.

The venom is "chemically unique", Fry said, which drives home the importance of biodiversity.

When fang blenny venom was analyzed researchers found three venom components. "While the feeling of pain is not produced, opioids can produce sensations of extremely unpleasant nausea and dizziness", says Brian Fry. So, the Meiacanthus genus of fang blenny evolved venom, co-opting these teeth from their ancestral action of scooping out chunks of flesh, for the delivery of venom to fight off potential predators or compete with other small fish for hiding spots in the coral.

Still, even a non-lethal effect is enough to allow blennies to escape their predators.

'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'.