Written by Rachel Sciberras – Form 1 St.Matthew

There are about 35,000 species of fish in the world, and some are very deadly. Sometimes people think that big sharks are the deadliest because they can kill a person with just one bite, but the truth is that some of the most deadly fish are quite small. Some of these small fish can kill a person in less than 1 hour with their poison. Let’s discover the 10 deadliest fish in the world.

1. Stonefish

This is the deadliest fish in the world. It is approximately 35 to 50 cm long. It is found in tropical waters including the Great Barrier Reaf and The Indian Ocean. Stonefish deliver their poison through the sharp spikes on their back. If a person who is poisoned by this fish is not given an antidote very quickly he/she can be paralysed and dies in less than one hour. Stonefish eat reef fish and small invertebrates.

2. Lionfish

Lionfish are very poisonous fish and they originated in the Pacific Ocean but now they are also found in other oceans. They are about 45cm long and have very bright colours. They have spiky fin rays which are poisonous. Lionfish stings can cause a lot of pain, vomiting and breathing difficulties. Although their stings do not usually kill adults, they are much more dangerous to children, old people or persons who suffer from allergic reactions.

3. Oceanic Whitetip Shark

These sharks live in tropical seas around the world. Their fins are white-tipped. Although the great white sharks, tiger sharks and bull sharks have more recorded attacks on humans, the oceanic whitetip sharks are generally believed to have killed the most people. This is because they often pick off the survivors of shipwrecks. One example is the USS Indianapolis ship which was sunk on the 30th July 1945 by a Japanese submarine. Out of the 890 crew which were stranded in the water until rescue arrived, about 150 of them were killed by oceanic whitetips, causing it to be the deadliest shark attack in history.

4. Great White Shark

These sharks have the highest record of unprovoked attacks on humans. They have an average length of 4.6 metres. They have an excellent sense of smell and can detect blood from 400 metres away. They are found in the coastal water of most oceans and regularly eat fish, whales and dolphins. Many scientists believe that great white sharks do not attack people intentionally but are simply doing a ‘taste test’ by taking a bite to see if they are edible. Unfortunately for humans even a ‘taste test’ can be deadly. 

5. Pufferfish

This fish ranges in size from 2.5cm long to more than 60cm. They are found in most tropical and sub-tropical waters and they inflate into a ball when they are threatened or disturbed. They have large spines on their skin which can only be seen when they are puffed up. This fish contains ‘Tetrodotoxin’ which is a powerful poison located in its liver, ovaries and intestine. One pufferfish contains enough poison to kill thirty adult humans and unfortunately, there is no known antidote.

6. Boxfish

The size of boxfish ranges between 25 and 60cm. They normally live in rocky and coral reefs in the Indian, Pacific and Atlantic oceans. They are distingushed by their box-shaped bodies. They have an incredible defence machanism to push away predators. They release a toxin called ‘Ostracitoxin’ through their skin into the surrounding water which becomes poisonous to anything nearby. This poison is very harmful to humans because it breaks down red cells. Also, some boxfish can cause death if they are eaten uncooked.

7. Moray Eel

Altough it looks more like a snake, the moray eel is a fish and it is very dangerous too. Whilst most of this type of fish live in the sea some are also found in fresh water. Most moray eels can reach 1.5m in length and they eat mainly squid and octopus. Divers are often attacked by them. Their teeth are very strong and sharp and are angled backwards to prevent prey from escaping. This makes their bites very painful and wounds bleed heavily. They carry a toxin in their slime and mouth which destoys red blood cells.

8. Wels Catfish

This fish lives in fresh water and can grow up to approximately 5m long. They are mainly found in lakes and rivers in Europe. Among other things they eat worms, insects, frogs and birds. Their mouths contain rows of small but very sharp teeth. Unfortunately, according to reports, this fish attacks and kills many people, usually fishermen and unsuspecting swimmers.

9. Goliath Tigerfish

This is known as the most dangerous fish in Africa. It lives in fresh water and feeds on anything it can catch. It is known as the african equivalent of a Piranha. This fish often attacks unsuspecting swimmers. Each tooth is about 2.5cm long and any teeth which are lost or broken grow again as a replacment tooth.

10. Candiru

A candiru fish is small but deadly and it is about 2.5cm long. It lives in fresh water in the Amazon Basin and is difficult to spot because of its translucent body. It feeds on blood and has a small head and body which can swell after eating. They have been known to swim up into the urethra of humans. Once there, they feed on blood and mucous membranes and lay eggs in the bladder, causing death unless removed.