Britain's Strangest Fishes
Britain's Strangest Fishes
From the intestinal breathing Spined Loach to the invasive behemoth Wels Catfish in freshwater, over to the grunting Grey Gurnards to the venomous weevers in saltwater, it's apparent that Britain is not short of strange fishes, but a lot of those unusual species you may have already heard of. What about Britain's strangest fishes; the sparse, enigmatic species that go by unnoticed, often for years, or decades at a time? The seas surrounding Britain's shoreline, and in the heart of our rivers and lakes, are home to over 400 fish species; over half of which even the most seasoned species anglers may not have heard of, or realise were or have been present here.
I'm tired of those thoughtless 'TOP 10' lists; AI slop made only for engagement bait. Recently I read one by a reputable publisher on 16 of the world's weirdest fishes, where somehow Cuttlefish made the list. Approximately 40,000 species of fish on the planet, and they couldn't even find 16 without supplementing it with a mollusc. Sure, some of them were weird, but it was mostly low hanging fruit (Blobfish, Flyingfish, Archerfish etc.), species we largely all know about—nothing that made you say "what the f*ck is that?". I want to send you down a Rabbitfish hole (yes, we have Rabbitfish too) by showing you some top contenders for Britain's strangest fishes. Of course, many fishes have their own highly unusual quirks, but the catch I'm hoping here, is that these are the strangest ones you've [probably] never heard of (naturally, a lot of them will be deep-sea).
1) Deep Sea Duck (Nemichthys scolopaceus)
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| Nemichthys scolopaceus ©Monterey Bay Aquarium |
Nemichthys scolopaceus ©George Brown Goode
Whatever you'd like to call it, Slender Snipe Eel or Deep Sea Duck, it's worth noting that it is neither a snipe, and surprisingly nor is it a duck. It is however, from the sea's depths, incredibly slender, and thanks to it's long, thin snout, is named after the wading 'Snipe' birds. This species of unusual true eel (belonging to Anguilliformes) is widespread in tropical and temperate seas, and their most northerly range includes Ireland and the east coast of Britain. While seldom, if ever reported here, their range is so expansive, they are expected, and in their northern ranges, can even be sighted higher in the water column, than their usual midwater (between 200–1000 metres) depths. They tend to travel up and down the water column to feed (unlike other members of this genus which are unable to), and their long, highly specialised 'beak' is a clue as to what they feed on and how—catching small shrimp-like crustaceans! They have quite radical sexual dimorphism too, in where once the males reach sexual maturity, their jaws undergo a dramatic shortening, and they loose all their tiny, villiform teeth.
2) Beaked Spookfish (Dolichopteryx rostrata)
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| A similar species of Spookfish, not found in Britain, Dolichopteryx longipes, ©OCEANA |
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| A drawing of our native (British) Spookfish, Dolichopteryx rostrata. ©Sergei A. Evseenko |
As this species is so rare, described only from a single specimen collected just west of the Hebrides islands in Scotland, photos of them are hard to license (I only have this drawing). Photographed above, instead, is the Brownsnout Spookfish (Dolichopteryx longipes) their closest distance to Britain, only as far as the north coast of Spain. If the snout of the Brownsnout is comparable in breadth to an American Alligator, then the snout of the Beaked Spookfish is closer to a Saltwater Crocodile. This species is arguably the most alien-looking on the list, with their translucent body, and almost luminescent innards, they resemble a giant, radioactive planarian flatworm; and those splayed pelvic fins also remind me of wings to create drag for some weird, alien craft that needs to land. A fascinating feature of this genera, is that their telescopic eyes start off soft and malleable, and once they've formed, part of them begin to harden, in a process called sclerotization (the same process which insects use to harden their exoskeleton).
3) Armed Gurnard (Peristedion cataphractum)
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| Peristedion cataphractum collected onboard an oceanographic research vessel ©Carmen B. de los Santos |
I hear you, gurnard are weird, but are they deserving of this list? I'm assuming you've heard of the Red, Grey, and Tub Gurnards, and some of the more 'species mad' of you might be aware of the much rarer Streaked, Flying, Longfin, and Piper Gurnard in Britain. Of course, they're all deserving, simply due to the fact, that many of them have separated the lower fin rays on their pectoral fins to feel around the seafloor, often appearing like they're "walking", but what makes the Armed Gurnard stand out above them all, is the presence of large, protective scutes, and that their preorbital splits into a snout which has two ends. They range from the English Channel, all the way down to Angola, which I think is quite fitting, as it looks like they're compatible with type-C plug sockets; it's just a shame they're not an electrical species.
4) Half-naked Hatchetfish (Argyropelecus hemigymnus)
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| Argyropelecus hemigymnus ©Dante Fenolio |
With an expression like that, you'd think the Half-naked hatchetfish was in a perpetual state of realising it is half naked, so please nobody tell them, they, like all fishes, are fully naked. Thankfully, they are absolutely miniscule, so nobody would notice their lack of clothes anyway, barely reaching a humble 5cm maximum. Similar in shape, but no relation to the freshwater hatchetfishes (Gasteropelecidae) like you see in the aquarium trade, these guys have much larger mouths and hang deeper in the water column. They are distributed across most of the world's oceans, frequenting between 150–380 metres, and completely surround Britain. The depth they inhabit has led to one of my favourite adaptations in British fishes—counter illumination. This is where they use bioluminesce to dazzle predators, so they can escape; more famously known to have developed in some species of squid.
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Argyropelecus sp. in Ireland, showing off its counter illumination. Photo ©RV Celtic Explorer |
5) Prussian/Gibel Carp (Carassius gibelio)
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| A Carassius gibelio I caught in Cornwall, identified by Prof. Mark Everard, and Jack Perks; meeting every discerning criteria listed by the IFM. |
It's not all about looks, some of the strangest fishes can appear pretty normal; even as inconspicuous as a goldfish. That's effectively what the Prussian Carp are, a slightly drab looking, big goldfish. If you ask anyone to draw you a fish, they're probably not going to be far off from this. Ironically, what makes this fish so unique, is their persistent ability not to be—they clone themselves! Females of this species can hybridise with other species of carp, and maybe other cyprinids too, however the sperm of the other species, only stimulates the egg to develop, in a process gynogenesis, so the DNA from the father is not passed down, meaning the offspring is not actually a hybrid, and is effectively a clone of the Prussian. This caused serious concern over their potential for being highly invasive in Britain, as if they're present in a lake with other cyprinid species, they may breed out other carp from the water given enough time. It has been hypothesised that they may be more widespread in Britain than previously thought, and this has since been confirmed, with Prussians now identified in the east Midlands, London, and even Cornwall.
6) Angular Roughshark (Oxynotus centrina)
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| Oxynotus centrina ©Nunzio Bellantoni |
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| Photo credit: someone's kid (I hope) |
With over 40 species of shark in Britain, 44 by my count (not including Ghost Sharks, which are Chimaeras), I had to include at least one shark to this list. You know those sketches of a car which a child would draw from memory, and they appear blocky and out of proportion? Angular Roughshark are like the shark version of that! Most photos which exist of this pig-nosed species, have been of specimens pulled from the depths by trawlers, where their large, personable eyes have puffed red from barotrauma; upsetting to see, especially so as the IUCN lists this species as Endangered globally, and Critically Endangered in the Mediterranean; although they have been reported from the west of Ireland, and even in Cornwall too! In comparison to their body, they have some of the largest, most elongated spiracles of any shark species, not just in Britain, but globally; and interestingly, they have a defensive spine in each dorsal, to protect them from predators. This is a feature you usually see in ray-finned fishes, as it's easy for a supporting fin ray to evolve into a spine, simply by hardening; however cartilaginous fishes do not have fin rays, so each spine evolves from elongating a single dermal papilla (the toothy structures which makes a shark's skin so rough).
7) Ferocious Boa Dragonfish (Stomias boa ferox)
Stomias boa ferox ©Alex Ingle
Perhaps my favourite on this list is the Boa Dragonfish subspecies, the Ferocious Boa Dragonfish; the only dragonfish taxa we have in Britain, namely in the North Atlantic. Visually, they're a feast for the quirky fish-lovers! You have this jet black body with large, iridescent scales; needle-like teeth; a tasseled barbel, acting as a lure on their jaw; and a serpentine body—they almost resemble a xenomorph's secondary jaw (Alien, 1979). S. boa ferox is distinguished from its prototypical species by having more photophores behind their eyes and scattered across their body. They're one of the few deepwater taxons on this list, which is more accurate to say are occasionally deepwater. Every day they come up from the blackness of 500–800 metres into water as shallow as 10 metres (potentially following the food), in an occurrence called diurnal vertical migration. Next time you're talking about migratory British fishes, rather than mentioning the b o r i n g horizontal migration of eel, salmon, and shad; how about the vertical migration of Ferocious Boa Dragonfish?
8) Deepsea Lizardfish (Bathysaurus ferox)
Bathysaurus ferox ©NOAA National Ocean Service
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| Bathysaurus ferox ©NOAA National Ocean Service |
I pride myself in loving all fishes, even some which people deem 'unloveable', but this one is testing me; pure nightmare-fuel. It looks like some sort of zombified crocodile. I'd hate to be that creature's lunch; well I'd hate to be any creature's lunch, but if I was a fish, and the last thing I saw coming at me was a John Dory, or that haunted-looking Deepsea Lizardfish, I'm getting digested by the John Dory every time! It's a good job this lizardfish doesn't get much bigger than 2ft, otherwise deepsea or not, I'm avoiding the ocean! Basically black metal bichirs—is it odd that I still want one... or ten, in my aquarium? Deepsea Lizardfish are considered one of the deepest living apex predators in the world, and with that elongated bony head, they are both effective ambush predators and short burst pursuit hunters. Due to their size, and lack of food on the seafloor, they tend to be sparsely populated, with a study in 1985 suggesting that there may only be up to eight individuals across each 25,000 square metre area in parts of the Atlantic.
9) Long Snouted Lancetfish (Alepisaurus ferox)
Alepisaurus ferox (photographer unknown)
The Dimetrodon of the fish world, this species has a remarkably large, sail-like dorsal, and belongs to an order of fishes dating back 125 million years, the Aulopiformes—just like the Deepsea Lizardfish! Another similarity you might've noticed, is that some taxa on this list share the name ferox. This name is applied to four different species in Britain; five if you count Ferox Trout (Salmo ferox) as its own species, like Freyhof & Kottelat (2008) and Hughes, Martin Robert (2017) do. The name ferox means fierce, and is usually given to species which are particularly voracious, and in the case of the Long Snouted Lancetfish, their garish appearance, paired with their cannibalistic behaviour, certainly earns that title! That highly aggressive feeding behaviour can also be their downfall in the modern age; whilst not being fussy about food (sometimes preying on conspecifics), they will even eat plastic! Though native to subtropical and tropical waters, they migrate as far north as the arctic, entering seas around the British Isles; this migratory behaviour opens them up to new feeding grounds, and further exposure to plastic pollution. Approximately 30% of all Long Snouted Lancetfish are believed to consume plastic, which they tragically are unable to digest.
10) Atlantic Torpedo Ray (Tetronarce nobiliana)
Tetronarce nobiliana ©karmer, iNaturalist
Earlier in the article, I mentioned electric fishes; now we all know about Electric Eels, and some aquarists are familiar with the Electric Catfish, and Black Ghost Knifefish; the latter of which can discharge electricity faster than anything in the animal kingdom. However, these are either from South America, or Africa; but what about Britain? Well, meet the Atlantic Torpedo Ray; a species of strange, disc shaped electric ray, ranging as far north as Scotland. They have highly concentrated, localised areas of electroplaques, which store electricity in their tissue like a battery, and when hunting, they pulse up to 220 volts of electricity to stun their prey. Human interest in this species has gone back a long time: since the 1970s, electric rays have been studied to help us understand how the synapses in our brain work and interact with eachother; in the 17th and 18th centuries, long before they were described to science, the oil in their liver was used to fuel lamps; and the electrical impulses from live specimens were even used by the Romans and Ancient Greeks to treat ailments like gout, migranes and epilepsy.
Now this is just a list of ten of Britain's strangest fishes, there are so many more! Puffers, lumpfish, chimaeras, snipefish, clingfish; there are so many to choose from (invasive, migratory, deepwater, encroaching from climate change etc.), which I'll cover in future articles. Hopefully there was a few on this list I've introduced you to for the first time, and if you're lucky enough to come across any, you can recognise them well enough to assist in identification. Which species on this list was your favourite?
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