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The Three Most Common Fish in the Sea

Cyclothone Bristlemouth
Cyclothone Bristlemouth

With an estimated over 800 million to 2 billion tonnes of fish biomass swimming in our oceans at any one time, that’s a lot of scaly swimming creatures to be counted.  However, unless you’re a marine biologist, or a quiz facts aficionado, your first guess on this one was probably wrong. The most common fish in the world is one the vast majority of people, except fishermen and scientists, have never even seen. Even the two most caught fish around the world today might be unfamiliar to Western seafood fans – although you’ll probably recognise their genus name.

Cyclothone Bristlemouth

The Cyclothone Bristlemouth is not only the most common fish in the world, but probably the most common vertebrate animal of any kind too. Marine biologists estimate that there may be upwards of several trillion of these shiny 3-inch long little guys swimming around in the ocean right now. So how come you’ve probably never heard of them before?

Well, it might have something to do with the depth at which they usually live – some 1000 feet, or around 0.4 miles, below the ocean surface. At this depth, the ocean environment is relatively similar all around the world. This allows Bristlemouths to flourish in almost any part of the world’s oceans. They’re also not particularly edible, due to the phosphorescent sacs that line their upper bodies, and the depths at which they live. So, it’s no wonder most people don’t know them – but there are certainly enough of them about. In fact, even if you took the conservative estimate of the number of rats in the world and then added that to the human population, you’d still fall about 10 million times short of how many Cyclothones there are. And that’s just one species of Bristlemouth, of which there are about 10 – although Cyclothones are the most common.

Grass Carp
Grass Carp

Grass Carp

The most commonly caught fish in the world, with over 5 ½ million tonnes of this single genus farmed every year. They are a hugely popular seafood dish in China, where they are farmed because they are easy to keep at a range of temperatures and they grow extremely quickly. Farmed Grass Carp average out two to three feet long, but some wild examples have been found at over 6 feet in length. They were once native only to South-East Asia, but their natural diet of freshwater weeds means they have been introduced as a pest control species all over the world – and can now be found across Africa, Europe and North America.

Peruvian Anchoveta

This fish holds the world record for the most amount caught (by biomass weight) of a single fish type in any one year – over 13 million tonnes of them were dredged up in nets throughout 1971. Their stock has fallen considerably since then, somewhat understandably. The Peruvian Anchovy is one of the most found ingredients in fish meal, the ground paste made from by-catch that is used to feed farmed fish, pigs and other livestock.