Catch Report: Small-Headed Clingfish | Unratified British Record
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| Small-headed clingfish (Apletodon dentatus); look at those beautiful green eyes! ©Joshua Pickett |
"As far as I'm aware, this is only the third ever rod and line capture of this species, and the first on bait"
Clingfishes are among my favourite groups of fish, and for the weird-loving, piscine enthusiast, it's easy to see why. Belonging to the order Gobiesocoidei (no relation to gobies), and within the order Blenniiformes (some relation to blennies), they comprise almost 200 species across the world! They have big, personable, and sometimes vacant-looking eyes; a beakish snout, and they're virtually all mouth. The feature of their namesake, however, is their adapted pelvic fins which form a large sucking disc, so strong, that when ultra-light anglers hook into a clingfish, they often assume they're snagged.
British Clingfishes
There are four species of clingfish in British waters, each just as interesting as eachother; we have the Connemarra clingfish (Lepadogaster candolii), which has been reported cleaning other fishes (I wrote a feature for Sea Angler on how to catch this species); the Cornish sucker (Lepadogaster purpurea), our largest species, which has two bright blue ocelli on the dorsal side of their head, and is not restricted to just Cornwall; the Two-spotted clingfish (Diplecogaster bimaculata), a deepwater species, occasionally seen by divers, but seldom from the shore, unless washed up after a storm; and the Small-headed clingfish (Apletodon dentatus), our smallest clingfish species, and one I've just caught on rod and line!
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| Connemarra clingfish (Lepadogaster candolii). ©Joshua Pickett |
Historically, some authorities have counted the Shore clingfish (Lepadogaster lepadogaster) as being present in Britain, but the common name Shore clingfish has been erroneously applied to Cornish suckers too, and that has led to some confusion that Lepadogaster lepadogaster resides here, when in fact, what we have is the near-identical Lepadogaster purpurea. I've discussed this in more detail in an article from 2024.
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| Cornish sucker (Lepadogaster purpurea). ©Joshua Pickett |
In 2023, I caught my first clingfish species, the Connemarra; it was my 35th British species, and I've since gone on to reliably target, and guide people onto catching them. It was around this time, that Will Pender caught a Small-headed clingfish during The Big Lerf Winter League; he was the first person (at least on record) to catch this species, and on a lure too [23 Feb 2023], that just cemented my obsession to 'crack' the clingfish code. For the next three years, I paid attention to shore and dive surveys, and made notes of where they're found; what sort of habitat they like; what they eat; and looked to see if there were any trends. The year following Will's capture, Scottish angler, Andrew Seywright hooks into a Small-headed himself [May 2024]; this is starting to look a little more viable now. In 2025, I put some of that research into action, and tried for one of the larger clingfishes, the Cornish sucker, and on my second attempt, I caught two individuals (my 66th species); one of which was glued onto the stone so tight, I thought my cheb weight was stuck between the rocks, and I didn't think I had a fish on.
The 'Leg-Work'
Having now caught two of the more common clingfish species, my attention turned towards the Small-headed, which was perfect timing, as the information I had gathered on this species was showing clear trends. Surveys had sporadically been reporting this species in rock pools, primarily on large low tides, and appearing in greater number between the months of February–April; citizen scientist sightings appeared to corroborate this (like those on iNaturalist, see figure below).
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| Small-headed clingfish sightings on iNaturalist, 1 Jan 2023–21 Mar 2026. ©Joshua Pickett |
I believe the significant boost in iNaturalist sightings from 2024 to 2025 is a combination of several factors. The first being that rising sea surface temperatures could be allowing them to spawn earlier in the spring, allowing them a longer period for which this temperate species is able to spawn in Britain. This is something we've suspected for decades in fishes, however a more recent paper has confirmed this is the case, at least for temperate species. The second reason for the spike, would be the increase of active users on iNaturalist; although this only accounts for a 6.8% increase overall, and the number of observations between February and April remained largely the same for both years. The final reason, which I think accounts for the biggest proportion of a jump in Small-headed clingfish observations, is the sudden popularity in nudibranch hunting. The very 'Instagrammable' Rainbow Seaslug (Babakina anadoni) was first reported in Britain in 2022, and by 2025, their numbers had exploded to the point where you had a very good chance of finding them rock pooling. Spurred on by TikTok and Instagram influencers, amateur naturalists flocked to the rock pools on big low tides to find them. Nudibranchs can be found all across the intertidal zone, but you will tend to find more in rock pools near the waterline on a big low tide, and it's often these nudibranch hunters who are finding Small-headed clingfish. Interestingly, nudibranch and rockpool hunters are primarily active throughout the spring and summer months, so you would expect them to continue reporting Small-headed clingfish well into the summer, but we don't see that, which suggests that by late spring, the vast majority of these clingfish have moved from the intertidal zone to the nearshore—or the very least have gotten better at hiding!
The Hunt
Now with the information and tools to find them, I put several sessions into seeing if I actually could. I started the 2026 season early (in January), joined by Cal, finding only a juvenile Cornish sucker. At 2.5cm, the size you can expect for most Small-headed clingfish, I initially thought this could've been the target. Nevertheless, I tried to see if there was any bait or lure it would take, as I had figured that clingfish this small, living in the same area, regardless of species, would be eating more or less the same food. Subsequent trips proved fruitless, until there was a rise of sightings in late February. I wanted to go on the next big tide, but the weather had been terrible (we had rain every single day of 2026 up to this point), and I already had plans anyway. Independent to this, our friend Caleb went searching for nudibranchs in early March, and came across a Small-headed clingfish. I waited for the next weather window, and saw a very big tide coming up, so me and my partner Becca, decided to do a bit of nudibranch searching for ourselves—armed with my pink tanago rod, I very much had the clingfish in the back of my mind.
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| Perfect conditions and prime clingfish 'hunting' grounds. ©Joshua Pickett |
It was approximately 40 minutes before low, so I started with the rock pools as close to the waterline as I could get away with. Knowing that the clingfish would be hidden under rocks, I gently lifted them to inspect what was underneath, before placing the rocks back exactly as I found them. The species diversity never fails to excite me; we found so much life: Edible, Velvet swimmer, Porcelain, and Montagu's crabs; Squat lobsters; Cushion and Brittle starfish; Snakelocks anemones; Worm pipefish; rockling sp.; Rock gobies, Common blennies; Cornish suckers; and several nudibranchs with their egg ribbons (Aeolidia and Aplysia sp.); great fun! Surprisingly quickly I find a Small-headed clingfish (a good sign), it was clasped to the underside of the rock, I go to take a closer look at it, and it jumps off the rock and completely vanishes from sight (this is going to be tougher than I thought). I find several more, most of which were around 2cm, which even for my tanago hooks, appeared to look too big for them.
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| Two of the Aeolidia sp. we found that day. ©Joshua Pickett |
Now, when it comes to my rock pool fishing, I will avoid disturbing the environment as much as possible. Not only are these areas low tide shelter and breeding grounds (or battlegrounds depending on the species), it can be some of the hardest fishing there is, and if you go around moving rocks, it can take an hour or more before those fishes settle and have calmed enough to take a lure or bait—some rock pools might not even be exposed for as long as an hour! However, when targeting a nearsighted species that is not much larger than 2cm, on rod and line, you need to focus your time and attention on an incredibly small area of the rock pool, and if you bait or lure is mere milimetres in length, it's important you're in the exact spot. For this reason (and for this species), you don't have much choice but to gently inspect under rocks.
When lifting rocks, wear protective gloves, and avoid large or heavy rocks, as the jagged edges and sharp barnacles can leave deep, nasty cuts on your palms and fingertips.
Top to bottom Connemarra clingfish, Cornish sucker, Small-headed clingfish (dorsal view). ©Joshua Pickett
The Clingfish Trifecta
Eventually, I found another clingfish, on the underside of a flat rock. Not wanting for this one to vanish into the ether, I lowered the rock slowly back into the water and worked my tanago hook on a 1.5g cheb weight around the edges and gaps under the rock itself. I was using tiny pieces of ragworm which I bought and cut up from my local tackle shop, Lowen Chy. "Small-headed clingfish? You've been after them a while", Fletch remarked, but the clingfish didn't come out to take even their highest quality rag. I thought that they're probably not even seeing such a tiny bait, until I found one clingfish around the 4cm mark (pretty much full-grown). This one was right on the underside edge of a rock, with part of its body and head peeking out from underneath. I could see one of its eyes move to look at the bait, and frustratingly the fish remained still, taking no interest whatsoever. At this point, if it's not working, change! I noticed that every rock I turned up which had a Small-headed clingfish under, also had lots of tiny amphipods, presumably Bivalve scuds (Melitidae sp.), could this be what they're feeding on? I didn't have a net on me, and these things were too small to pick up by hand, so I found an empty limpet shell and scooped up a single scud. I hooked it onto the tanago through the tail, and returned to the rock which had the clingfish underneath, now it has had a bit of time to rest. I couldn't see the fish anymore, but assumed it had moved slightly further under the rock and was just out of my view. I worked the scud around the same gap, twitching the hook roughly every ten seconds, and after what felt like an age, the the clingfish eases out and hoovers up the bait. I am so relieved that when I lifted the tanago rod, the clingfish didn't do what it does best (cling onto the rock), as the hook-hold was so light, it just would've pinged out! What a cool catch, and this makes it my 87th British species on rod and line! After catching the clingfish, I stopped fishing and continued to search for nudibranchs, and by the end of only two hours down the rock pools, we found no less than seven Small-headed clingfish! I think we may have seen more too, as when you lift a rock, they're so easy to confuse with prawns in the corner of your eye, as both will jump off into the water (and that happened a lot).
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| Small-headed clingfish (Apletodon dentatus); the only picture I got before the rest of the scud fell off of the hook. ©Joshua Pickett |
As far as I'm aware, this is only the third ever rod and line capture of this species, and the first on bait (at least in Britain). It's so easy to see why, it's a challenging species to find and catch, and equally difficult to identify without placing them in a viewing tank. As I was taking these photos, I saw them swinging and pushing their tail against the base of the viewing tank; it looked like they were trying to propel themselves off of the surface—I wonder if this is how they jump?
With the first catch of this species being unmeasured (appearing sub 3cm); the second being 3cm; and this capture at 3.9cm, it is an unratified British record.
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| A full-grown Small-headed clingfish (Apletodon dentatus); notice the small, posterior set dorsal fin, a discerning feature from Connemarra and Cornish sucker which has a longer dorsal fin. ©Joshua Pickett |
How to discern the Small-headed from the Two-spotted?
It sounds like it should be obvious; the Two-spotted clingfish has two large spots (one either side of their flank), and the Small-headed will have... well, a small head. Unfortunately, it's not that simple. Two-spotted clingfish don't always have two spots, and both species have the same head structure. In fact, their morphology is virtually identical when you're only inspecting them in the field, and in much of their ranges, their markings overlap; what a nightmare! The most reliable way to tell them apart is by their teeth: the Small-headed will have, at the front of their mouth 2–3 sharp, vampiric canines either side of their small, rounded incisors; whereas the Two-spots have more uniform teeth with no elongated canines. However, without a magnifying glass or a macro lens, this is something you're going to struggle to observe in a fish which is sub 4cm.
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| Circled (red) are the sharp canines distinct to the Small-headed clingfish (Apletodon dentatus). ©Joshua Pickett |
The most reliable way I know of, for citizen scientists, is ecotypical colouration and location. Two-spotted clingfish are somewhat rare in the intertidal zone, but are more common in deeper water, whereas the opposite is true for the Small-headed. In the lower end of the nearshore (around reefs and structure) is where they overlap the most, and in turn so do their markings. Though, the markings in the Small-headed clingfish photographs I've provided are typical for them in the intertidal zone, and these intertidal markings do not occur in any known Two-spotted clingfish populations, so if you encounter one which looks like the above pictured, it's probably a safe bet that it's a Small-headed, not a Two-spotted.
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| Two-spotted clingfish (Diplecogaster bimaculata), with one of its two, large distinctive spots on the flank (a species I'm yet to catch). ©Jim Greenfield |
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