This fish’s opium-like venom could lead to new pain medications

Most venoms cause pain. This one inhibits it.

Fang blennies are a tropical fish that won’t be intimidated, injecting predators and competitors alike with venom released from two long teeth on their lower jaw. New research reveals that rather than stunning foes with a jolt of pain, the venom acts on the bitten fish’s opioid receptors, causing it to become dizzy and lethargic. This offers an entirely new avenue for the development of novel painkillers. We spoke with Bryan Fry, a biologist at the University of Queensland, about his findings and the chances this newly discovered resource will survive the effects of climate change on the Great Barrier Reef.

ResearchGate: Why do fang blennies have venom?

Bryan Fry: While we have known for a long time that fang blennies exist, their venom system has remarkably never been investigated. Their ancestor was a fish that used its fangs to scoop out flesh from larger fish, much like today’s bluestriped fangblenny, which mimics the bluestreak cleaner wrasse. When a larger fish goes after one, thinking it’s going to get a wrasse, they get close enough scoop out a chunk of their would-be predator.

These big teeth were also the perfect structure for delivering venom, thus providing selection pressure for the evolution of venom. 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.


Skull of the venomous species Meiacanthus grammistes. Credit: Anthony Romilio

RG: What did you find when you studied their venom?

Fry: The venom is absolutely unique; we have never seen anything like it. This research reveals a novel source of opioid painkillers. These peptides were not selected for this use in the fish, but rather evolved because they also cause hypotension dizziness and induce uncoordination. However, the next step is now to study them further and continue sequencing them. This may reveal new painkillers that are longer lasting, more potent, or have fewer side effects.

RG: How does this venom compare to that of other animals?

Fry: Defensive venoms, whether those in cobras or in stingrays, are well known for their extreme pain-inducing action. This venom is very different in that it is pain-free.

RG: What could the loss of the Great Barrier Reef do to this species?

Fry: My fear is real. These fish are found on the Great Barrier Reef, so their existence is as threatened as that of the reef itself. The inaction by governments the world over against climate change threatens not only natural wonders such as the Great Barrier Reef, but also the vast economic potential contained within.

The opioid angle is indeed the key here. This discovery is an excellent example as to why we must urgently protect all of nature. It is impossible to predict where the next wonder drug will come from. The Great Barrier Reef is currently dying due to the effects of climate change, and the Australian government has been shockingly inactive in responding to this threat. Destroying the reef is no different than popping a nuclear bomb on top of an oil field. It is the willful destruction of a vast economic resource.

Featured image courtesy of Bernard Dupont