Estuarine Stonefish

The Estuarine Stonefish, Synanceia horrida, has a formidable reputation of being the most venomous fish in the world, it also has a suitably menacing visage to go with its Latin name “horrida”. They have a large head with protruding eyes and mouth, they also have sunken cheeks giving them a skeletal appearance. Their mottled bumpy skin can change color to blend into their surroundings and allow them to disappear when hunting their prey or when hiding from predators. The mucus on their skin and their sedentary ambush behavior encourages algae to grow all over their body, further enhancing their camouflage.

In Australia “Horrida”, which can grow up to 60cm in length, generally inhabit coastal reefs, lagoons and estuaries along the northern reaches of the continent. They make depressions in the mud, sand or loose coralline gravel by digging with their large pectoral fins. “Horrida” lies motionless in the mud during the day, waiting to ambush small fish and crustaceans that wander into their reach. When their prey gets quite close, “Horrida” snap open their mouth and lunge forward in a fraction of a second, engulfing their hapless victim. “Horrida” is reputed to have one of the fastest attacks in the animal kingdom.

Unlike reptiles, insects and arachnids, which use their venom for offensive purposes, “Horrida” only use their venom as a defensive tool. “Horrida” cannot readily escape their predators, as they are relatively poor swimmers. So they have to rely on camouflage and the strong deterrent of their venom to get themselves out of tricky situations. Like most Venomous marine animals, they are very reluctant to use their venom as it is one of their only forms of defence. Once used it takes some time to regenerate so they must use it sparingly.

When Humans and “Horrida” interact it is usually a negative experience for one or the other. If you happen to stumble upon one in the wild, please respect it and keep a good distance away. The last thing you want to do is to scare one into a defensive frame of mind. The sting from “Horrida” is instantly incredibly painful, radiating up the affected limb. The pain is always associated with rapid swelling and sometimes necrosis at the sting site. The toxin can damage muscle in the immediate area and go on to affect the heart and respiratory system. The sting can cause death in extreme cases.

The best way to deal with a sting is immediate first aid. Stay calm and still, immerse the injured area in hot water (test it with a non-affected limb first, as the toxin numbs the affected area you may further injure yourself with a burn) this will dull the pain. Always go to the hospital to be treated with anti-venin. On the other side of the coin “Horrida” are caught and sold for their meat in Hong Kong, and made into “okoze” sashimi in Japan.

Here at Sydney Aquarium, I have gotten to know our resident “Horrida” “Stoney” over many years. I must say I have grown to see the nicer side of him through many great positive interactions. I still always chuckle to myself when I feel the jolt of surprise as “Stoney” snatches the fish or prawn I am offering him from the end of the feeding stick. He’s so quick that in ten years I can’t really say I have ever seen him actually take it. All I can say is it was there in front of his mouth then it was gone.

🙂