The deadliest fish in the marine world are often innocuous and appear harmless.
People globally are dependent on fish or products derived from fish for food and economic sustenance.
This post is an attempt at Ocean Conservancy and advice to divers to be adequately aware of some of these deadliest fish in existence.
There are more than 30,000 species of fish that roam the seas and freshwater bodies. Some of them are extremely beautiful and colorful, as on display in aquariums.
A few species, though, have terrifying and darker aspects. Some may attack human beings, and others deliver venom if carelessly handled or prepared for consumption improperly.
Myth and folklore play their role in maligning some species going by their terrifying looks.
The most important thing to remember is these harmful traits are triggered only as a defence mechanism. They don’t lie in wait to harm you.
I list below some kinds of fish which you can admire from a distance. They have been chosen after much deliberation as they are lesser-known.
15) Puffer

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The Puffer goes by many names- Swellfish or Blowfish. In Japan, they are considered a delicacy. When aggravated, it puffs up with air and water, assuming a rounded form. Puffers are mostly found globally in seas that are warm and temperate. However, you may encounter puffers in fresh or brackish water.
Their skins are tough and prickly. The teeth are fused, resembling a beak, with a break in the middle of each jaw. The largest recorded size of o puffer is 3 feet, but usually, they are a lot smaller.
Most species store a deadly toxin- tetrodotoxin, in the internal organs. Therefore they qualify as one of the deadliest fish.
In Japan, a chef undergoes special cleaning training to ensure that the fugu is safe for consumption.
14) Red Lionfish

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The Red Lionfish is truly beautiful to behold. But don’t let that get the better of you. Their quills contain a venom that may not kill you, but you sure would wish you were from the pain.
The native habitat is the South Pacific. Over time, the migration to the reef systems along the Eastern seaboard of the US came along. The East Atlantic, especially the Caribbean, is where you can most likely encounter the red lionfish.
With no natural enemies combined a high reproductive rate, they decimated all local fish. They got tagged as invasive fish legally as a result.
Experienced divers avoid any direct contact. The newbies may be exposed.
When disturbed, they spread their fins to ward off attackers. Next, if the aggravation continues, the enlarged dorsal fins get into firing mode.
They are not large, 12” at best, and concerning hobbyists took to them.
There appears to be evidence that many were released into the waters off Florida by pet owners in the 1980s. However, the real damage came from Hurricane Andrew in 1992 that let them out into the sea.
13) Sea Snakes

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Sea snakes are anything between 30-50 species. They inhabit the Indian and Pacific oceans predominantly. At an average length of 2 meters (6.5 feet), they belong to the cobra family. They are not aggressive creatures, though.
Their venom is deadly. The toxicity is such that three drops can kill eight people. This catapults them into the realm of one of the most deadliest fish though strictly speaking they belong to the reptile family.
12) Cone Snail

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The cone snail is an unlikely species to come to mind as a dangerous customer. They are around 10-15 cm in length but have deadly venom, three drops that can kill 20 people. They look charming and are any shell collector’s delight. But cone snails are not aggressive. Instead, being slow on the move, they harpoon their prey. The lethal venom follows.
They inhabit the Indian and Pacific oceans. However, deep reef waters are favored. So they have somehow sneaked into the Caribbean and the waters off Florida.
Do not fool around these guys. They have an alias, “the cigarette fish.” That is about the time you will get if you mess with them.
11) Stingrays

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This creature came into prominence after the demise of Steve Irwin, the famous TV host ‘croc hunter.’Their saw-edged tail holds the venom. These tails are whip-like and long; a few different stingrays families are not of our concern.
They inhabit all oceans but especially South American rivers.
They are, on average, 2 feet in width and around 7 feet in length.
They are bottom dwellers, semi-buried to feed in dead mollusk beds. Most accidents occur as a result of being stepped on inadvertently- the tail lashes out and kaboom.
10) The Atlantic Manta Ray

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The Atlantic Manta is the largest of the family of manta rays. The largest can span 23 feet. It is usually brown or black.
Ecuador and the Galapagos Marine Reserve is their habitat.
Mantas are powerful but inoffensive, contrary to tales that mantas swallow humans whole. They feed on zooplankton.
They are of particular value in the international trade for their gill rakers.
The NOAA (National Oceanic and Atmospheric Administration) and the ESA (Endangered Species Act) classify them threatened.
9) Stonefish

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A stonefish is a bottom sweller and sluggish. Stonefish usually dwell in coral, among rocks and mudflats. They populate the waters of the Indo-Pacific.
Stonefish are bottom dwellers usually resting on the bottom, unmoving and blending effortlessly with the surroundings.
These guys are pretty dangerous. They are not spottable easily. If stepped on, they inject through dorsal-fin spines.
The sting can be excruciating. Death can result too.
8) Moray Eel

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Moray eels are pretty fishy customers. They mostly abound in tropical and subtropical waters, frequent shallow waters, and can reach 12 feet.
They are different from other eels. They lack pectoral fins and gill openings that are small and rounded. Instead, the mouth is broad, with jaws are lined with sharp, strong teeth that they use to catch prey.
When disturbed, they can inflict severe wounds on humans. The consumption of Morays is a practice in some parts of the world, but the flesh is sometimes toxic, resulting in death.
7) The Big White Shark

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The White Shark is one of the most predatory and dangerous creatures of the oceans.
Much maligned and feared, it is also little understood.
White shark concentrations are primarily in coastal waters that are abundant in fishes and marine mammals. These are the coasts of northeastern and western United States, Chile, northern Japan, southern Australia, New Zealand, southern Africa, and the Mediterranean.
White sharks are large, bulky torpedo-shaped fish with a large conical snout, pectoral and dorsal fins. A sizeable crescent-shaped tail and you have the ultimate killing machine.
They have solid muscles, excellent eyesight, and a keen sense of smell as hunters.
The massive jaws have huge sharp pointed teeth. The design of the coarsely serrated teeth can saw through bone and flesh with ease.
They can be as long as 21 feet weighing anything between 1500 t0 4000 pounds.
As for attacks on swimmers, divers, kayakers, and even small boats, unprovoked incidents are common.
Researchers claim these attacks are more out of curiosity or where their natural prey is scarce.
6) Barracuda

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There are about 30 species of Barracuda. They are found in warm and tropical waters and sometimes in temperate waters.
They are swift and powerful. The lower jaw of the Barracuda juts out and has a formidable array of large sharp teeth. Typically they vary from 4-6 feet. They are primarily fish eaters.
They are bold and curious, with the enormous variety a potential danger to humans. Swimmers have come under attack by White sharks.
5) Salt-water Crocodile

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Salt-water crocodiles possess the ability to survive in full salinity seawater. They, however, prefer to inhabit brackish waters close to the coat.
They can reach lengths of over 23 feet and can weigh over 2200 pounds. It is the largest reptile on the planet. Salt-water crocs have powerful jaws and teeth that, on average, are 5 inches long.
The salt-water crocodile is territorial by nature and will spring to the attack. As a reason, they have been known for many attacks on humans.
4) Tiger Fish

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Several species fall under the umbrella of tigerfish. They are so named for their pugnacity when caught, their ferocity as predators, and their appearance. They are identifiable with long, dark stripes running the length of the body.
In freshwater, tiger fishes win admiration as game fish. Their teeth that appear like daggers protrude from the mouth even when it is closed. About five species exist. The largest could exceed 6ft in length and weigh more than 125 pounds.
The smaller varieties have sharp spines on the gill covers that can wound by careless handling.
3) Piranha

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Piranha is also known as caribe or piraya in South America, where they are native. There are about 60 species of piranha. They are razor-toothed carnivores. Their reputation for savage ferocity is somewhat exaggerated. In reality, most species are scavengers and plant feeders.
2) The Chironex Box Jelly, or The Australian Box Jellyfish

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The box jellyfish is the deadliest, most venomous marine animal. If one of the 6 feet long tentacles as much touch you, death will kick in before you reach the shore.
Another species imparts a sting so painful you will beg to die. The pain, headaches, vomiting, and anxiety are beyond excruciating. It will result in the accumulation of fluid in the lungs and ultimately death.
These species frequent the waters of the Indo-Pacific, specifically the waters of northern Australia. However, sightings are on report off the Gulf Coast, the East Coast, and Hawaii.
About 50 species, each having 15 tentacles, armed with 5000 stinging cells. These stingers can fire the toxin at around 37 mph into their prey. In humans, this causes a massive spike in blood pressure. Heart arrest follows rapidly.
Their prey is shrimp and small fish.
1) Blue-Ringed Octopus

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The Blue-ringed octopus is so innocuous in looks that it is often grossly underestimated. With its kaleidoscopic coloring, this pint-sized creature gives it a cuddly appearance, hardly a cause for alarm.
Don’t let this fool you. This cute gut can kill you and fast.
It is native to the Pacific Ocean, often seeking refuge in the sandy bottom of shallow tidal pools and coral reefs. When seeking prey, the coloration changes rapidly, and bright blue rings emerge to warn predators.
The blue-ringed octopus is part of an elite league. Its venom is a thousand times as potent as cyanide and can decimate 26 humans within minutes.
It too produces the deadly neurotoxin, tetrodotoxin, same as the pufferfish.
In humans, this toxin first causes numbness of the muscles by blocking nerve signals. Then, nausea, vision impairment or blindness, loss of senses, and motor skills follow. Finally, it leads to muscle paralysis, inability to breathe, and respiratory failure.
There is no antidote. So it is best to back off if you spot one. Blue-ringed octopi are not aggressive and only spring into defense mode when cornered or mishandled.
.Sources: https://www.britannica.com/