Life of Sea | Estuarine Stonefish(Synanceia horrida) | Estuarine stonefish is also called Hollow-cheek stonefish. This species typically lives in coastal foreshores. It also lives in waters that are subject to salinity fluctuations and often carry a high sediment load. These conditions provide a muddy substrate. Estuarine stonefish use it to camouflage themselves from predators and potential prey by burying themselves in the silt or sand, with only their mouth slit protruding. This fish can be tracked from one sunken ambush site to another by following impressions left in the mud by the fish hopping across the bottom on its pectoral fins. The species is coastal areas of the Indo-West Pacific: India to China, the Philippines, Papua New Guinea and Australia, and is also recorded in Vanuatu.
Estuarine stonefish can grow up to 50cm, those seen about 15-20cm. The eyes are close together with a bony ridge between them. It has a deep depression below each eye. The huge mouth faces upwards and is curved into a perpetual frown. The skin is leathery with prominent warts on the sides. It is also found in muddy places and estuaries. It is drab in colour, brownish to reddish brown, which aids in its ability to camouflage itself among the rocks of many of the tropical reefs. During the day, it lies motionless on the sandy bottom, in a shallow depression that it creates by scooping sand out and piling sand around its sides with its pectoral fins. At night, it is more active and often moves on top of reefs.
As stonefish, Estuarine stonefish are carnivores but don't actively hunt their prey. Instead, they lie motionless, relying on their camouflage to remain undetected. When a suitable snack comes close enough, they suck it into their huge mouths, or grab it with a sudden lunge of incredible speed. They generally eat fishes and crustaceans.
The stonefish is one of the most dangerous fishes on ocean. It has tough dorsal fin spines that can penetrate thick soled shoes. These act like hypodermic needles, injecting a venom that can be fatal to humans. Stonefishes produce neurotoxin that is considered the most deadly of the fish venoms. An emergency first aid is to apply heat to break up the toxins. But the victim should be brought to hospital as soon as possible. There are few documented cases of fatalities. The fishes use their spines in self-defence and not for hunting prey.