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Stone fish are the most poisonous (venomous) fish in the sea and one of the most dangerous and even fatal to humans in the world. Local names include, Totovu/Bunju/Nungu/Bevuama Bevi. In the underwater world, an organism does have to be the largest creature to be the biggest threat. The stonefish, which reaches an average length of 30 to 40 cm and weighing up to two kilogramsare the most venomous fish in the world having venom sacs (glands) on each of their 13 spines. Although the threat to responsible divers is minuscule (little). Five (5) facts one may need to know about these interesting toxic underwater critters (“living creatures”) should you come across them are:

  1. Four (4) species in the familySynanciidae (Stonefish), Genus Synanceia that are frequently found in the coastal regions of the Western Indian Ocean include:
  1. As the most venomous fish species in the sea, many of us would assume that stonefish kills its prey using the venom in their spines, but instead, the stonefish capture their prey with speed. To capture food, stonefish wait for their prey to appear and then swim fast and quickly attack. The attack can last as little as 0.015 seconds! When not chasing their prey, the stonefish normally swim very slowly.
  2. Having excellent camouflage capabilities, the stonefish are very difficult to notice. It’s often exciting to spot the most disguised critters when diving, therefore you must be keen enough to be able to notice one hiding in the rocky seafloor or coral.
  3. Stonefishdo not go out of their way to attack, they rather usetheir poison as a defense mechanism against predators. The venom is usually released when pressure is applied to the stonefish’s spine, which means the poison is most often emitted when the stonefish is being attacked by a predator or stepped on. If for whatever reason you accidentally step on a stonefish, seek immediate treatment as the venom can cause severe pain, heart failure and even death if left untreated.
  4. Stonefish can survive up to 24 hours out of water, which is an uncommon trait among fish. Reef Stonefish (Synanceia verucosa) the most common species in our beaches grow to 35 cm in length, although 50 cm specimens have been reported.

Stonefish camouflage and can blend so perfectly with their surroundings such that their prey, predators, even human SCUBA divers and beach users have trouble seeing them. They almost always sit perfectly still, on the sea floor, in their preferred habitat of coral and rocky reefs, where their colours are often a perfect match to the substrate. Some individual stonefish have even been observed having algae growing on them. While camouflage gives them further protection from predators, its primary purpose is to allow stonefish ambush their prey. They eat other reef fishes and some bottom dwelling invertebrates, but they do not actively pursue these animals. Instead, they wait for dinner to come to them. Waiting for hours at times, stonefish strike when their potential prey is less than their body length away. Their powerful jaws and large mouths create so much pressure that they are able to suck down their unsuspecting prey and swallow it whole.

Stonefish are only rarely eaten by some people, and there is no target fishery of any of these species, although some individual species are sometimes caught for the private and public aquarium trade. Population trends of the group are not currently known, but there is no evidence to suggest that human activity threatens the stonefish population. However, as human activity and environmental variations continue to threaten coral reef habitats, it is important that scientists carry out research on this group of marine organisms to ensure that populations are in fact stable.

Caution to BeachUsers

Avoid just picking up anything on the beach especially something that resembles a rock, estuaries are the hot spots. It is not normalto find stonefish in clean sandy beaches frequently visited by swimmers. Stonefish prefer more sheltered areas such as around rocks and weeds, where they can sit down on the bottom half bury themselves in the substrate. They are fairly sluggish swimmers and don't like to be buffeted around by the waves. To stay safe if working or playing in rocky areas is to wear good foot protection. The thin rubber sole variety aren't ideal for stonefish as the spines may penetrate through, but they will provide some form of protection than being bare feet. If you are stung by a stonefish, you will "know about it very quickly in seconds the pain builds up, it becomes excruciating (unbearable) in minutes.

Treatment of Envenomation

Envenomation is the exposure to a poison or toxin resulting from a bite or sting by an animal such as a snake, scorpion, spider, insect or marine life.Stonefish stings are extremely painful and potentially lethal. The two most recommended treatments are the application of heat to the affected area, and administration of anti-venom. Hot water (at temperature not higher than 45o C (113o F) applied to the injured area has been found to denature stonefish venom resulting in minimal discomfort. Vinegar readily available in some local shops near frequently visited beaches is said to lessen the pain. Anti-venom is used in more extreme cases. Hot water and Vinegar can be used for temporary relief however seeking medical attention and anti-venom is the essential to do.