The seabed is home to some of the most poisonous fish on the planet, including one that is deadlier than a cobra snake. Nature has given us many good things, especially in the marine world, but we must be careful when enjoying this habitat and especially the food it provides. In this article we invite you to identify them.
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The world’s most poisonous fish
The oceans are home to most of the planet’s biodiversity, the meeting place for many of nature’s wonders, this habitat also provides us with a large amount of food, but we must be careful with this matter, because here we can also find the most poisonous fish, and if we do not know them, we can lose our lives if we come into contact with them in any way.
Below we present a selection of these species, which we will learn about their characteristics in order to be able to distinguish them and appreciate their ecological value.
Astronomical fish
The Sindoscopus australis or Astronomical Fish is found only in the southern Pacific Ocean, off the coast of Chile, and is considered to be one of the most poisonous fishes, as well as giving an electric shock to anyone who comes into contact with it.
This fish is considered an endemic species, which means that its presence is recorded in only one geographical area, and that there are currently no conservation measures in place, although the area where it is found is protected.
The astronomer fish measures between 20 and 90 centimetres in length and has a characteristic facial appearance, with eyes located at the top of the head, pointing towards the sky, it has a large mouth, also located at the top of the face, this peculiarity allows it to live under the sand and hunt its food, its colour is similar to mud.
It is found only on the southwestern Pacific coast of Antofagasta and Metrien Bay in Chile, and is often found under the sand in shallow waters.
During the day it can be found under the sand, while at night it feeds on smaller fish.
The poison of the Astronomer’s Fish is contained in stingers in the pectoral fins and the operculum, a bone that protects the gills and serves as a marker to separate the head and trunk of the fish. The potency of this venom is fatal to humans, making it one of the most poisonous fish on the planet.
In addition to the lethality of its venom, the astronomical fish is considered to be electric and generates discharges through glands called electrolytes, free ions that act as electrical conductors, located in its muscles and generate electricity of about 50 volts, which is not lethal but is very shocking to humans.
Surgeonfish Zebraoma
Surgeonfish Zebrasoma is a very popular reef fish that refers to underwater forms that are created from the shells and skeletons of corals, molluscs, etc. Its diet is based on eating seaweed, its dorsal spine is erect, very sharp and it is considered one of the most venomous fish.
Although it is an edible fish, care must be taken with its handling and hygiene, as its improper handling can cause food poisoning with facial paralysis, body aches and hypotension, a low blood pressure that causes dizziness and a slow pulse.
It is about 40 cm long, with a rounded, disc-shaped body, fins on the dorsal and anal parts, a large head and a small mouth, and a blue and yellow colouring.
It has a pair of removable stingers on each side of its fins, hence the name Surgeon, which it only uses when it feels threatened by other fish or to defend its territory.
They can be seen in schools around islands, cays and coral lagoons at depths of 2 to 40 metres. They are mainly found in the Indian and Pacific Oceans, particularly along the coasts of Africa, the Red Sea, Australia and the Hawaiian Islands.
Their diet is based on plankton, microscopic living organisms from the sea, and they also feed on vegetables.
The male is slightly larger than the female, they are oviparous, meaning they hatch from eggs, and monogamous, meaning they have only one partner.
https://www.youtube.com/watch?v=UqENWcwa6A4
Stonefish
The Synanceia horrida, or stonefish, has spiny, scorpion-like scales and is considered one of the most poisonous fish in the world.
It is commonly found in the waters of the Indian and Pacific Oceans, especially in Australia and the Malay Archipelago, in shallow waters where there are reefs and coral walls.
The most significant peculiarity of this species is related to its physical appearance, as it resembles a sea stone, to which other characteristics of the fish are related:
- The colour of its skin varies according to where it is found, but a mixture of colours predominates: red, grey, green, yellow and brown, depending on where it is found, one of these colours will predominate.
- Its skin is hard and secretes a sticky fluid, which is why its body is regularly covered with algae and pieces of coral.
- Its eyes, located at the front of the head, are large. This is a common feature of hunting fish, as well as being alert to attacks by predatory fish.
- It has several fins, the dorsal fin has 13 spines, the anal fin has 3 and the pelvic fin has 2, all of which are venomous.
Its venom is deadly, all its spines contain a deadly gland called cytotoxin, which is related to the individual cells of the fish, and neurotoxins, which are related to the blocking of neuronal chemical impulses, it is deadly to humans.
After contact with the spines, the pain is penetrating and radiates throughout the affected part of the body, with maximum effect at the time of the event, as well as symptoms such as headache, nausea, intestinal pain, increased blood pressure with cardiac arrhythmias, muscle stiffness, convulsions and respiratory arrest.
If the person survives thanks to the use of the antidote, the wounds heal slowly and must also be monitored, as they may become necrotic, indicating damage to the muscle tissue, which may necessitate amputation of the affected limb.
Flower Urchin
Among the most poisonous fish are the echinoids, which are the red or flower urchins, characterised by their spiny skin, disc-shaped body, lack of fins and skeletal structure made up of several layers of calcareous plates that form the carapace in which the poisonous spines are located.
Flower urchins are normally found in all marine environments, both warm and cold, and are found on the bottom, although they prefer rocky formations and coral reefs.
The sea urchin is red in colour and moves very slowly over the seabed. It is characterised by being a herbivore, eating algae and plankton. It reproduces asexually, with the male and female releasing their gametes into the water where they unite to form an egg.
The hedgehog is often found in rocky areas, so it is well camouflaged in this type of environment, and when it is touched it releases a poisonous toxin, contact with the spines causes a very intense pain, followed by a burning sensation, depending on the amount of toxin in the body, headache, nausea, abdominal cramps and even haematemesis, the vomiting of blood.
As adults, these hedgehogs are protected from predators by the size of their hide and their spines, which are poisonous and protect them. However, there are some natural predators that have claws, teeth or pincers, but the hedgehog’s protective shield overcomes them.
Humans are also considered predators of this animal, since they use it as a staple food and, in other cases, as an ingredient in more specialised gastronomic recipes, such as: sea urchin caviar, pâté, soups, creams, sauces, ceviches, etc.
https://www.youtube.com/watch?v=fJAH5r-GcpY
Conus
In addition to the more poisonous fish, there are also gastropods such as the conus figulinus, better known as conus or conos, an invertebrate with a head, a soft body covered by a shell and a small foot muscle.
The shell ranges in size from 30 mm to 153 mm and is coppery in colour, with dark brown lines that are closely interlaced.
They are found off the coasts of the Indian Ocean, Madagascar, Mozambique, Mauritius and Tanzania, and can also be found in the western Pacific.
Conus contains poisonous elements called neurotoxins, which directly affect the nerve tissue of the neurons and are more powerful than cyanide.
It is popularly known as the “cigarette clam” because the time it takes for the toxin to take effect is the same time it takes a person to smoke a cigarette as a defence against its marine predators.
Blue-ringed octopus
The Hapalochlaena, or blue-ringed octopus, is an invertebrate mollusc of the cephalopod and octopus genus, as it has a mouth in the centre of its brain and eight tentacles. Generally found in the Pacific Ocean from Japan to Australia, it is considered a formidable competitor to the world’s most poisonous fish.
This octopus is characterised by its blue rings all over its body, although these colours can change to a light brown depending on where it is found, but when in danger it camouflages itself with a bright yellow covered in equally bright blue rings.
The size of the blue-ringed octopus is 20 centimetres long, but the flexibility of its body makes it very effective, as it has no bones and can move quickly.
It has been shown that octopuses have a high level of intelligence, which has allowed them to adapt to the changes that have occurred on the planet, and part of this evolution is in the changes in colour according to the level of stress they are undergoing, and the sac where the ink is located is also part of this process, as both conditions are a means of survival in the event of an attack.
Another characteristic of the blue-ringed octopus is that it is considered to be very aggressive, always ready to fight if provoked, for its food and its territory.
The venom released by the blue-ringed octopus is fatal to humans, and it has even been proven that this species can kill with its bite. The area where this species is found is rarely visited by divers and dive boats, as they are afraid of encountering this species.
They regularly hunt at night and their diet includes shrimp, crabs and fish. Due to the agility of their body and the capacity of their venom, the hunting process is very effective.
Although they are a solitary and aggressive species, this situation changes when it is time to mate, the males and females remain calm and ready for the mating action. Females produce around 50 eggs, which they keep in their tentacles until they hatch.
Male and female blue-ringed octopuses live for about a year and a half, with males dying a few weeks after mating and females dying within a few days of hatching.
The blue-ringed octopus has to contend with predators such as whales, eels and birds. Sometimes, however, the predators are hunted by their victims, as the octopus can sting them in the middle of a fight, immobilising them.
Xanthidae Crab
The Xanthidae crab is a crustacean, an invertebrate whose skeletal structure is external, covered by a calcified shell, equipped with a pair of antennae and several arms, reddish in colour and considered a worthy contender in this list of the most poisonous fish.
They measure between 9 and 13 centimetres, their skeleton is formed by an oval and flat carapace, the first pair of legs is used for defence, and the claws are slightly larger in males.
Xanthid crabs are generally found in the Atlantic Ocean, south of North Carolina, Florida, the Bahamas, the Yucatan Peninsula in Mexico and in the Caribbean countries of the West Indies.
They feed on plankton, which consists of decaying organisms such as dead fish, algae, oysters and marine worms.
The crabs have a two-year period to enter the reproductive stage; the females release a type of sponge containing between 200,000 and over a million eggs and can lay up to 6 sponges during the mating season.
The reproductive stage takes place between the months of May and October. During the mating season, the male crabs protect the female and do not allow other males to approach.
The female expels the eggs in the form of larvae, which are then transformed through metamorphosis, a rather complex biological process in which the embryos undergo a change in structure and physiology until they become a crab.
The Xanthidae crab is extremely poisonous, even these toxins are not eliminated by cooking food, and there is no known antidote for this type of poison.
The venom contains tetrodotoxin, a neurotoxin of marine origin that rapidly attacks the neurological system, and saxitoxin, a paralysing toxin produced by the algae. The poison produced by this species is as deadly as that of the most poisonous fish in the world.
Fugu
The fugu fish, also known as the pufferfish, has the peculiarity of swelling up by ingesting water as a survival measure, as it increases in size considerably, making it difficult for predators to eat it. It is considered to be one of the most poisonous fish on the planet.
Ranging in size from 30 to 50 centimetres, the fugu has small, thin spines that are hidden and only become visible when the fish swells, with females being slightly larger than males.
Its mouth is beak-shaped, similar to that of a parrot, with four large teeth in the upper and lower jaws, which are used to open the shells of crustaceans and molluscs.
They can be found on the planet’s tropical beaches, in shallow coastal areas they adapt to fresh and brackish water, which is a balance between the salt water of the sea and the fresh water of the lagoon. It is generally the type of water found in estuaries where rivers mix with the sea.
Fugu fish feed mainly on shelled animals such as clams, snails, crabs, sea urchins, seaweed and worms, and their powerful teeth are constantly renewed as they wear down from eating shelled animals.
During the mating season, the male makes circular pits in the seabed to attract the female to lay her eggs.
The fugu is considered one of the most poisonous fish in the world. Its venom consists of tetrodotoxin, which is found in the liver, ovaries and skin and acts on the muscular system, causing the victim to drown from inflammation of the throat muscles. There is no antidote.
Fugu fish produced in hatcheries do not show this toxicity, and scientific studies show that this situation is due to feeding in artificial and controlled environmental conditions that do not allow them to consume foods such as algae that contain high levels of this substance, known as tetrodotoxin.
Fugu is a very popular dish for human consumption in Japan, but due to its high toxicity, handling the viscera, the internal organs of the fish, must be done with great care as it can contaminate the preparation.
In order to serve it in commercial establishments, chefs must attend a legally recognised school, complete a three-year course and obtain a legal permit to handle and cook the fish.
Fugu is safe to eat in places where a permit is displayed for both purchase and consumption in restaurants. Fugu can be eaten in the following ways:
- Fugu no shirako.
- Sashimi.
- Deep fried.
- Stew.
- Salad.
- Pickle.
Cubozoa
Cubozoa or Cubozoaires are jellyfish, invertebrates with the shape of an umbrella. The venom produced by this species is one of the most effective, it is considered very painful and even fatal for humans, for this reason we will describe it in a complementary way in this list of the most poisonous fish.
Its main characteristic is its umbrella shape, as it has 4 cubomedes, which are the tentacles that give the dome the shape of a cube.
Inside the umbrella is the shutter, whose function is to regulate the flow of water, which allows them to move quickly, reaching a speed of 1.8 metres per second.
These jellyfish have real eyes made up of retinas, corneas and lenses located on either side of the tentacles.
The tentacles can reach up to 3 metres in length and weigh between 2 and 3 kg; each tentacle contains about 500,000 cnidocytes, a type of sucker containing nematocysts, a microscopic harpoon-like mechanism that injects venom into the victim.
Cubozoan jellyfish are mainly found in the tropical regions of the Indo-Pacific, Eastern Pacific and Atlantic Oceans.
The nematocysts in their tentacles, which contain their venom, are activated when they touch human skin, producing a large number of stings and a very sharp pain. The antidote serum contains acetic acid, a component of vinegar, which deactivates the venom from stings that have not yet entered the human bloodstream.
Even when the Cubozoaire jellyfish is dead, the tentacles continue to produce toxins, so care must be taken when removing them as they can still cause poisoning.
Striped sea snake
The Laticauda colubrina, or Striped Sea Snake, is a highly venomous marine reptile found in the warm tropical waters of the Indian and Pacific Oceans. Its body is easily recognisable in shades of light blue, similar to silver, with black stripes. They are excellent swimmers and divers.
Their bodies are cylindrical at the top and flat at the bottom, silver blue with black lines running from the neck to the end of the tail, which they use to give direction to their movements.
Female striped sea snakes are larger than males. They have a broad belly that is almost as wide as their body, a yellowish snout and a black head, while their eyes have a membrane that acts as an eyelid.
They have no gills, so they have to come to the surface to take in oxygen, but they can stay under the surface for up to 2 hours.
Their diet consists of crabs, cuttlefish, eels, fish, eggs and squid, which are common in the shallow waters of coral reefs and estuaries.
They are considered to be highly venomous, the venom they produce is estimated to be 10 times stronger than that of a cobra, they attack when they feel frightened; during the mating season they are very aggressive, the neurotoxic venom paralyses the victim’s muscles with the bite in a matter of seconds.
The fangs of this species are very small and the chances of being attacked are very low, but there have been a few accidents with fishermen being bitten while retrieving their nets and dying from the lethal effects of the venom.
Lionfish
The Pterois antennata, also known as the lionfish, is characterised by its reddish and white stripes. It is considered a violent fish and its bite is painful and poisonous, although not fatal.
It measures about 20 centimetres, has spectacular red and white stripes on its fins and chest and wide black and white antennae, and is considered the most poisonous fish.
This species is found in East Africa, off the coasts of Japan and Australia, and has recently been seen off the Caribbean in Venezuela. They are usually found alone on the seabed and during the day on rocky outcrops, reefs and coral areas. Its feeding time is at night when it often feeds on shrimp and crabs.
As one of the most venomous fish, its sting is considered dangerous as its venom glands are located in the stingers of the dorsal, central and anal fins, which are painful and the toxins produced cause pain, respiratory paralysis and fever, but are not considered fatal and the symptoms disappear after a few days.
This concludes our content on the world’s most poisonous fish, and we have also included other complementary species that we consider equally interesting. If you liked it, we invite you to visit our other articles through the following links:
- Pink Lagoon
- Niagara Falls
- Amazon River