The Biggest Fish in the World

We’re all about big fish stories here at MeatEater, and we recently came across the biggest one yet. At an estimated 70-plus-feet-long, Leedsichthys problematicus is thought to be larger than any other fish in history. In fact, there are only two living whale species that surpass that astounding size.

Now, before you go spooling up the 10-ton-test, you should know these incredible fish went extinct in the late Jurassic Period (about 155 million years ago). Remains of L. problematicus were discovered in the 1880s by British fossil collector Alfred Leeds, hence Leeds-ichthys, or “Leeds’ fish.” The species name, problematicus, derives from the difficulty of reassembling thousands of fossilized bone fragments and classifying the animal when complete.

Problematicus is thought to be a member of the Pachycormid family, an early branch of the bony fishes we know today. If that taxonomy is correct, it would make bowfin the closest living relative. But problematicus’ skeleton included a lot of cartilage and hollow bones that disappeared or were crushed over millions of years underground, leaving us with only fragmented, “problematic” remains. The largest of the 70-plus specimens discovered, known as the “Big Meg,” filled 20 museum drawers with its bones—more than 10,000 fragments from the tail alone. As such, the exact shape of the skeleton is not fully understood, leading to a great deal of disagreement over the facial structure and actual length.

Some early scientists posited that they could reach beyond 100 feet, while others suggest only 36. Current estimates hypothesize a maximum length around 54 feet, though some researchers insist the fish must have been longer.

One can only assume that those researchers are also anglers.

As with most modern marine monsters, problematicus was a filter feeder specializing in plankton and krill. Analyses of the specimens found in Germany, France, England, and Chile have revealed a large proportion of nutrients derived from microinvertebrates. It also appears from the fossil remains that the fish possessed large and expandable gill baskets and hyomandibula, allowing them to take in and filter massive amounts of sea water.

It would have taken a really tiny lure or fly attached to really, really heavy line to tangle with this massive fish. That seems like a particularly tricky rig to set up, and we’re not sure these fish even existed concurrently with humans, so the possibility of an actual fisherman every tangling with one of these beasts seems slim, at best. But when have we ever let details like plausibility get in the way of a good fishing story?

Feature image via Bogdanov, Wikimedia Commons