Fish Facts

General Fish Facts


    • Porbeagle, thresher, shortfin mako and blue sharks are all present in UK waters. Killer whales are also confirmed in UK waters as well.
    • With 32,000 species fish display more variation than any other vertebrate.
    • Fish have been on planet earth for 450 million years – twice as long as mammals.
    • The oldest fishing hook ever discovered was over 40,000 years old.
    • Lungfish, found in South Africa, Australia and South America, can live out of water for several years.
    • It is illegal to sell seaweed in the UK without a licence.
    • Under the UK’s Salmon Act of 1986 it is illegal to ‘handle salmon under suspicious circumstances.’
    • Eel is the number one pizza topping in Japan.
    • Baikal seals are only found in Lake Baikal, Siberia, 2500 miles from the sea. It is a scientific mystery how the seals got there.
    • Only 5% of the world’s oceans and seas have been fully explored.
    • Promachoteuthis sulcus is a species of squid which is know to science due to a single specimen caught in the South Atlantic.
    • Despite their fearsome reputation there has never been a confirmed human death caused by piranhas. Most of the horror stories about this species come from times when they have fed on the bodies of humans who have already died.
    • During their evolution the anus of the slender snipe eel has moved forward so that it is now located in their throat.
    • There is a resident population of killer whales in British waters. Around eight killer whales live and feed off the west coast of Scotland. However, they have not produced a calf in over 20 years and it is likely that they will die out within the next generation.
    • Shoals of herring can be one square mile in size and contain over one billon individual fish.
    • An 800lb bluefin tuna will eat around 12,000 smaller fish every year
    • Some species of anglerfish have black-lined stomachs to stop the bio-luminescent fish they prey on giving their position away.
    • Hagfish produce slime as a defence against predators. They can fend off sharks by producing so much slime that their attackers gills and mouth becomes clogged up, forcing them to retreat. See it in action here.
    • Electric rays, which are found in waters to the west of the British Isles, can give a shock of 220 volts.
    • Samsung – the world’s biggest electronics company – began as a dried fish exporter

Lifespan Facts

    • Ocean quahog – a species of edible clam – is the longest living species in the world, with a lifespan of 400 to 500 years.
    • In 2016 Greenland sharks were proved to live for at least 270 years, with researchers believing they could live for more than 500 years, making them the world’s longest living vertebrate.
    • The Hydromedusae jellyfish has a lifespan of just 3 to 5 hours.
    • The Beadlet Anemone (commonly found around UK coastlines and rockpools) has a lifespan of 60 to 80 years.
    • The common limpet found around the UK can live for over twenty years.
    • The deep sea species orange roughy can live for around 180 years and cannot reproduce until it is 30 to 40 years old.
    • The seven-figure pygmy goby fish has a lifespan of around 60 days, the lowest of any vertebrate species.

Poison and Venom Facts

    • The Estuarine stonefish is the world’s most venomous fish. Being stung by its spines injects a venom which causes immense pain, nausea, unconsciousness and can result in death. The pain is said to be so intense that people stung in the feet (by standing on the fish) have reportedly screamed for their foot to be amputated on the basis that this would be less painful than continuing to have the venom in their body.
    • The box jellyfish has vemon in its tentacles which is so potent that a human can die just three minutes after coming into contact with them.
    • The four inch long weever fish is the only venomous fish in inshore UK waters. The spines on its back inject a poison when they pierce skin. In humans this can cause intense pain, nausea and dizziness. It has, however, never reportedly been fatal in a healthy human.
    • The blue ringed octopus is smaller than a tennis ball but its venom can kill a human in minutes. There is no known antidote.
    • A single Chironex fleckeri (a species of box jellyfish) has enough venom to kill 60 fully grown adults.

Fish Size and Speed Facts

    • The Indo-Pacific sailfish can reach speeds of 70 mph (115 kph) in short bursts.
    • The eyes of a colossal squid are 1 foot (30 cm) in diameter – the largest in the animal kingdom.
    • The whale shark is the biggest fish in the sea. It can grow to 20 metres in length and weigh 20 tons.
    • The smallest fish which has a UK shore caught record is the common goby. Geoffrey Green holds the record with a 1 gram (0.035oz) specimen caught in 2007.
    • The largest fish which has a UK shore caught record is the common skate. G. McKenzie holds the record with a 169lb 6oz specimen caught in 1994.
    • At 20ft in length the giant pacific octopus is the largest in the world, although some scientists believe they could grow to double this size.
    • If left to grow to their maximum size cod can reach 6ft 6in in length and weigh 200lbs.
    • Monkfish can eat prey one and a half times their own size.
    • The largest bony fish in the seas is a disputed matter. The sunfish, king of herrings and European sturgeon all battle it out for this honour. At up to 60ft (18 metres) the king of herrings is certainly the longest, but the sunfish and European sturgeon beat it in the weight category.
    • The smallest fish in the world is a species of anglerfish called Photocorynus spiniceps. They are 7mm long when fully grown.
    • Giant squid have been confirmed as growing to 13 metres (42 feet) in length. However, sperm whales have been seen with wounds caused by fighting with giant squid, which indicates that there are giant squid in the depths of the world’s sea which are at least double this size.
    • Shortfin mako sharks (occasionally found in UK waters) can reach speeds of 40 mph and jump 25 feet out of the sea.
    • Growing to just 8 inches the dwarf lanternshark is the smallest species of shark in the world.
    • Bootlace worms found around UK shorelines are usually 6-7 metres long, but can grow up to 50 – 60 metres in length – putting them in contention as the longest animal in the world.

Reproduction and Breeding Facts

    • Female pacific blackdragon fish grow to 3ft in length, but males are only a few inches long. Males also lack teeth, a stomach or a digestive system and live long enough only to breed.
    • Silver eels do not develop reproductive organs until they are around 20 years old.
    • The Chromodoris reticulata sea slug disposes of its penis after reproducing and grows a new one as needed!
    • Female seahorses lay eggs in a pouch in the belly of the male, meaning the males effectively give birth to the young.
    • Only five in every 1000 seahorses reach adulthood.
    • All wrasse are born female. Around half turn male once they are aged 6-7 years old so that the species can breed and reproduce.
    • A fully grown cod can produce 2.5 million eggs when it spawns.

Blue Whale Facts

    • At ten feet in length the blue whale has the largest penis of any animal.
    • Blue whales are the largest creatures to ever live on planet earth. They can grow up to a maximum of 200 tons and 33 metres in length – larger than even the biggest of the dinosaurs.
    • Each of the blue whales testicles weighs around 150lbs.
    • Newly born blue whales feed on their mothers high-fat milk and can put on 200lbs in weight every 24 hours.
    • A blue whales tongue weighs around three tons.
    • The arteries of a blue whale are 10 inches in diameter.

Mantis Shrimp Facts

    • The mantis shrimp has the most complex eyes in the animal world. Mantis shrimp have sixteen different types of cells in their eyes (humans have three) They can see in three directions at once from each eye and can see ultraviolet wavelengths which humans are completely blind to.
    • The claws of the mantis shrimp are so powerful they can lash out at prey with the force of a .22 calibre bullet and strike their prey with 1500 Newtons of force.
    • When a mantis shrimp punches with its claws it uses so much force that the sea around the edges of their claws actually boils. The shockwave produced by the punching motion of the mantis shrimp can kill prey, even if there is no contact from the claws.
    • Aquariums and tanks holding mantis shrimps need to be made with specially reinforced glass as they can easily punch through the glass of a normal aquarium.

Conservation and Commercial Fishing Facts

    • Around 70 million sharks are taken from the seas by commercial vessels every year. An estimated 38 million of these have their fins removed and are returned to the sea to die with 95% of the edible flesh wasted. Increasing demand for shark fin soup from China is only going to see this number increase.
    • Humans take an estimated 80 million tons marine life from the world’s seas and oceans every year.
    • This 80 million tons of marine life equates to approximately 7,000,000,000,000 (seven trillion) individual sea creatures taken from the sea every year.
    • During World War 2 there were plans to drawn up to feed people with plankton to avert food shortages.
    • About 75% of the world’s fish species are consumed by humans. The other 25, however are still caught commercially and used for fishmeal, pet food, fertilizer or other products such as glue.
    • If the world’s commercial fishing fleet was halved in size overnight it we would still catch so many fish with the remaining vessels that the world’s seas would still be considered to be fished in an unsustainable manner.
    • In the 1600s only the Dutch were allowed to sell eels in London. Being able to sell this lucrative seafood with no competition was their reward for feeding Londoners in the aftermath of the Great Fire of London.
    • Annelies IlenaI (ex-Atlantic Dawn) is the largest trawler in the world. It is 144 metres long, displaces 14,000 tons and is powered by two 9,600 bhp engines. It can catch, process and freeze 400 tons of fish every 24-hours.
    • Sharks kill 6 humans per year. Humans kill 100 million sharks per year.
    • Up to 7% of fish on sale in the UK is thought to be mis-labelled. Usually coalfish or pollock is passed off as the more expensive cod or haddock.
    • Estimates state that illegal and unregulated fishing cost the world’s economies $10 – 20 billion (£6.3 – 12.76bn) a year and puts 260 million jobs at risk.
    • The global trade of seafood is worth £83 billion a year, making it one of the world’s most valuable commodities. Rising demand, particularly from China, is set to see this number increase in the near future.
    • 59% of the fish sold as tuna in the USA is not tuna. Cheaper snapper and escolar are the main species passed off as tuna.
    • With an annual catch of nine million tons the Peruvian anchovy is the world’s most exploited fish.
    • In 1950 around 19 million tons of fish were caught commercially on a worldwide basis. By 1990 this has risen to 80 million.
    • McDonalds sells 275 million Filet-O-Fish portions every year.
    • There has been concern that dams and flood defences block fish migrating between freshwater and the seas since at least the 1100s.
    • Every year commercial long-liners set 1.2 billion baited hooks in the world’s seas and oceans.
    • The Japanese are the world’s highest consumers of fish. On average each person eats 66kg a year. China is second with an average consumption of 56kg.
    • Due to overfishing, barriers to migration and natural environmental changes the Europes’s population of silver eels has reduced by 95-98% in less than three decades.
    • Every year the EU gives out around €1.6 billion in subsidies to commercial fishing vessels.
    • It takes 20 kilos of wild-caught seafood to raise a 4 kilo salmon in a fish farm.
    • Commercial fishing is by far Britain’s most dangerous industry. For every 100,000 people working as commercial fishermen 103 will die at work. This is 50 times higher than the average UK worker and makes being a commercial fishing more dangerous than being a firefighter, police officer, construction worker or any job within the UK’s armed forces.

Sea and Ocean Facts

  • Seas and oceans make up around 71% of the world surface.
  • The Mariana Trench in the Pacific Ocean is the deepest known point in the world’s oceans. It is 10,971 metres (35,994 ft) deep.
  • The Caspian Sea – which is located between Russian, Azerbaijan, Iran, Turkmenistan and Kazakhstan – is the largest enclosed body of water on planet earth. It has a surface area of 143,000 square miles and a volume of 18,000 cubic miles. Although it is saline it is less salty than the average ocean and it is debated whether it is the world’s largest lake or a fully fledged sea.
  • The Dead Sea is located between Jordan, Palestine and Israel. It is so called because the salt levels are so high (eight times higher than most other seas) that no marine animals or vegetation can live in it.
  • There are 1386 million cubic kilometres of water on earth. Saltwater accounts for 97.5% of this.
  • The mouth of the Amazon river is as wide as the Thames is long.
  • Only 0.5% of the world’s seas are protected from commercial exploitation.
  • 41% of fish species live in the world’s freshwater, despite that fact that it accounts for only 2.5% of water on the planet.
  • There are 1386 million cubic kilometres of water on earth. Saltwater accounts for 97.5% of this.
  • The average depth of the world’s seas and oceans is 2.5 miles.
  • The Aral Sea (between Kazakhstan and Uzbekistan) has been shrinking since the 1960s due to irrigation work which has stopped rivers flowing into it. Once the fourth largest enclosed body of water in the world it is now just 10% of its original size.
  • No one really knows how many different species of creature live in the world’s seas and oceans. Scientists have discovered and charted around 300,000 creatures so far – but estimate the total number of species could be in excess of one million.
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