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Stonefish: the world's most venomous fish, and where it is

The stonefish is the most venomous fish known, and it is effectively invisible — it sits motionless on reef flats and sandy bottoms looking exactly like an encrusted rock. Nearly every sting is the result of someone standing on one in shallow water. The pain is described as among the worst in clinical medicine.

  • 2High risk
  • 5Medium
  • 6Low
  • 13Zones tracked

What happens

Thirteen dorsal spines drive venom into the foot under the victim's own body weight. Pain is immediate and excruciating, with rapid swelling that can spread up the whole limb. Serious envenomation can cause vomiting, breathing difficulty, irregular heartbeat and collapse. Deaths are rare where antivenom is available, but the sting is a genuine medical emergency rather than a bad afternoon.

Where it lives

Shallow tropical Indo-Pacific waters: the Coral Triangle, northern Australia, the Red Sea, Thailand's Andaman coast, the Philippines and the Maldives. It favours reef flats, rubble and estuaries — the wading depth, not the diving depth.

How to avoid it

  • Wear thick-soled reef shoes for any wading on tropical reef flats or rubble.
  • Shuffle your feet instead of stepping; never walk on a reef barefoot.
  • Do not pick up or turn over rocks in shallow tropical water.
  • Take particular care at low tide, when reef flats are shallow and stonefish are trapped in place.

If it happens

  • Immerse the limb in hot water, around 45°C, for 30–90 minutes — this breaks down the venom and is the immediate priority.
  • Get to a hospital urgently; antivenom exists and is effective.
  • Remove visible spines, and keep the person still and monitored.
  • Treat every stonefish sting as an emergency even if the pain eases — systemic effects can develop later.

General guidance only — not a substitute for medical advice or local emergency services.

Where we track it

13 zones in the Dangers Here hazard database, by danger level.

High

  • Indonesia (Coral Triangle)
  • Northern Australia (NT Coast)

Medium

  • Maldives
  • Papua New Guinea
  • Philippines (Visayan Reefs)
  • Red Sea (Egypt & Saudi Arabia)
  • Thailand (Andaman Coast)

Low

  • French Polynesia
  • Great Barrier Reef
  • India (Western Coast)
  • Singapore (Southern Reefs)
  • Southern Japan (Okinawa)
  • Sri Lanka

Questions

Where is stonefish a risk?

We track 13 zones for this hazard. 2 are rated high risk, including Indonesia (Coral Triangle), Northern Australia (NT Coast). 5 are rated medium and 6 low.

How do you avoid stonefish?

Wear thick-soled reef shoes for any wading on tropical reef flats or rubble. Shuffle your feet instead of stepping; never walk on a reef barefoot. Do not pick up or turn over rocks in shallow tropical water.

What is the first aid for stonefish?

Immerse the limb in hot water, around 45°C, for 30–90 minutes — this breaks down the venom and is the immediate priority. Get to a hospital urgently; antivenom exists and is effective. Remove visible spines, and keep the person still and monitored.

What happens

Thirteen dorsal spines drive venom into the foot under the victim's own body weight. Pain is immediate and excruciating, with rapid swelling that can spread up the whole limb. Serious envenomation can cause vomiting, breathing difficulty, irregular heartbeat and collapse. Deaths are rare where antivenom is available, but the sting is a genuine medical emergency rather than a bad afternoon.

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