Shanny vs Rock goby
How to tell them apart, and what follows from getting it right.
Why they get confused
They are not alike. They are in the same net. Both are small, brown, mottled, blunt-headed bottom fish that come out of the same British rock pool at the same size, and for anybody who has just turned a stone that is the entire basis of the confusion — proximity rather than resemblance. It is made worse by the fact that both change colour with the ground and with mood, so the two things a beginner reaches for first, colour and size, are exactly the two that do not work. The good news is that the real answer is easier than either: this is one of the very few identifications in British fishing that is genuinely binary, and once seen it is never forgotten.
Shanny
Lipophrys pholis — Blenniidae
No photograph of Shanny has passed identity review yet, so none is shown. A photograph is published only once somebody has checked the animal in it against the diagnostic features described on this page.
Rock goby
Gobius paganellus — Gobiidae
No photograph of Rock goby has passed identity review yet, so none is shown. A photograph is published only once somebody has checked the animal in it against the diagnostic features described on this page.
The differences
Each difference is marked with how far it can be trusted on its own. A single diagnostic character settles the identification; suggestive ones only narrow it.
| Character | Shanny | Rock goby | Reliability |
|---|---|---|---|
| How many dorsal fins are on the backIdentification | ONE, running most of the length of the back. It has a distinct notch in the middle, and that notch is the trap — a notch is not a gap, and a notched fin is still one fin. Follow the fin rays with a finger and they are continuous through it. | TWO, with a clear gap of bare back between them: a short rounded fin at the front and a longer one behind it. Not a notch, not a dip, but two separate fins with nothing between them. | Diagnostic on its own |
| What is on the belly between the pectoral finsIdentification | Two small separate pelvic fins, reduced to a few rays each, sitting ahead of the pectorals like a pair of short fingers. Nothing joins them. | A ROUND SUCKER DISC. The pelvic fins are fused along their edges into a shallow cup, which the fish uses to clamp onto rock in surge. Turn the animal gently in a wet palm and it is unmistakable. This is definitive for every goby against every blenny. | Diagnostic on its own |
| What it does when you find it, before you touch anythingIdentification | Wedged INTO something — a crevice, the underside of a stone, a mass of weed — and staying there. It can survive out of water for hours in a damp crack, which is why you often find one on a stone rather than in a pool. | Sitting ON the bottom of the pool or on a rock face, flat, propped on its pectoral fins, and darting a short distance before stopping dead. The stopping dead is the sucker being used as a brake. | Supporting — use with others |
| Anything on the head, and the shape of itIdentification | Blunt, rounded, and — on a shanny specifically — completely smooth, with no tentacles at all. The other British blennies do carry head tentacles, so a tentacle means blenny but no tentacle does not mean goby. | Broader across the top, with the eyes set higher and closer together, and never any tentacles. A rock goby also carries a pale, cream or orange band along the upper edge of the front dorsal fin, which is the best colour mark any British goby offers. | Supporting — use with others |
| Where on the shore, and how far downRange | All round Britain and Ireland on rocky shores, from the mid-intertidal down. The default fish under a British stone, and present as far north as Norway. | All round Britain and Ireland too, but on average a little lower on the shore and rather more southern and western, and running south to Senegal and through the Mediterranean and Black Sea. A pool with both is entirely normal, so range does not settle a single fish. | Supporting — use with others |
| What either of them needs from you once caughtHandling | Wet hands, forceps rather than fingers, and back into the pool it came from — shannies home to their own patch of shore, so a fish moved elsewhere has been displaced rather than released. In spring and summer the stone you lifted may carry a male on a nest of eggs. | Identical, and for the same reasons. Rock gobies are site-attached too, and their nesting season runs earlier — late winter into spring — so the stone matters at a slightly different time of year. Put every stone back the way it was. | Supporting — use with others |
Why it matters
Neither of these fish can hurt you, and the third small fish in the same pool can. A long-spined sea scorpion is broad-headed, propped on large pectoral fins and carries sharp spines on the gill cover and the head that will go into a hand closed around it. The habit worth building on a shanny or a goby, where it costs nothing, is the one that matters on a sea scorpion: do not close a hand around a small fish you have not identified. And beyond safety, this is the identification that makes rock-pooling into something other than a repetitive afternoon: a child who can separate a blenny from a goby has been given a skill that transfers to every fish they will ever look at.
The full records
This page compares two species. Each of them has a complete record covering biology, behaviour, handling and the evidence behind all of it.
More about shanny
Where it lives, how it is caught, and what else it is confused with.
Similar and related fish
How it is caught
Where it lives
- Mudflats and intertidal sandflatsWhere rock and soft ground meet, shannies occupy the hard fragments and the pools within a flat rather than the sediment itself.
- Rocky shores and reefsUnder stones, in pools, in crevices and among weed from the mid-shore down — the commonest fish on a British rocky shore and the one under most rocks.
Why the 6 connections on this page are here, and the sources
Similar and related fish
Backed by research — 2 connections
Supported by peer-reviewed research or fisheries science. The sources are listed and can be checked.
Montagu's blenny
Coryphoblennius galerita has a fringed transverse crest across the top of the head; Lipophrys pholis has no head tentacles at all, which is unusual among the blennies and is its own identifying character. Both occur on western English and Channel shores, and both are what a child catches in a pool.
- FishBase: a global information system on fishes — Froese, R. and D. Pauly, eds. — FishBase Consortium (Scientific institute)Relied on for: The morphology, size, depth range and distribution that separate these two species from one another.States this directlyPassage read and verified
Rockpool blenny
Lipophrys pholis is the rockpool blenny of northern European shores and Parablennius parvicornis is the Macaronesian one. They occupy the same niche on different coasts, and an angler who knows one will recognise the behaviour of the other immediately.
- FishBase: a global information system on fishes — Froese, R. and D. Pauly, eds. — FishBase Consortium (Scientific institute)Relied on for: The morphology, size, depth range and distribution that separate these two species from one another.States this directlyPassage read and verified
How it is caught
What experienced anglers do — 2 connections
Widely and independently recommended by experienced anglers and specialist sources. This is real angling knowledge, not proof: controlled evidence for it is limited, and FishingHQ records it as convention rather than as a demonstrated effect.
Light rock fishing
A statement about how a species is fished or collected, which is convention rather than biology and is labelled as such.
- Sea Angler — Bauer Media (Specialist angling publication)Relied on for: Contemporary UK sea angling and shore gathering practice as reported by practitioners: ground, tackle, presentation and seasonal timing.States this directlyCitation checked — the work exists and is described correctly
- General angling website restatements of established technique — Various (Credible secondary source)Relied on for: Widely restated descriptions of technique, fish behaviour and regional practice, recorded as consensus rather than as scholarship.Background and mechanism onlyCitation checked — the work exists and is described correctly
What anglers actually use a method for, recorded as convention.
- Sea Angler — Bauer Media (Specialist angling publication)Relied on for: Contemporary UK sea angling and shore gathering practice as reported by practitioners: ground, tackle, presentation and seasonal timing.States this directlyCitation checked — the work exists and is described correctly
- General angling website restatements of established technique — Various (Credible secondary source)Relied on for: Widely restated descriptions of technique, fish behaviour and regional practice, recorded as consensus rather than as scholarship.Background and mechanism onlyCitation checked — the work exists and is described correctly
Float fishing
A statement about how a species is fished or collected, which is convention rather than biology and is labelled as such.
- Sea Angler — Bauer Media (Specialist angling publication)Relied on for: Contemporary UK sea angling and shore gathering practice as reported by practitioners: ground, tackle, presentation and seasonal timing.States this directlyCitation checked — the work exists and is described correctly
- General angling website restatements of established technique — Various (Credible secondary source)Relied on for: Widely restated descriptions of technique, fish behaviour and regional practice, recorded as consensus rather than as scholarship.Background and mechanism onlyCitation checked — the work exists and is described correctly
Where it lives
Backed by research — 2 connections
Supported by peer-reviewed research or fisheries science. The sources are listed and can be checked.
Mudflats and intertidal sandflats
A habitat association resting on the standard regional reference works rather than on angling report.
- The Fishes of the British Isles and North-West Europe — Macmillan, 1969 (Reference work)Relied on for: Distribution, habitat association, identification and biology of the fishes and inshore fauna of the British Isles and north-west Europe.States this directlyCitation checked — the work exists and is described correctly
- FAO Species Identification Guides for Fishery Purposes and the FAO Species Catalogues — Food and Agriculture Organization of the United Nations (Scientific institute)Relied on for: Diagnostic characters, family placement, habitat and depth range as set out in the FAO species identification sheets for the region concerned.States this directlyCitation checked — the work exists and is described correctly
Rocky shores and reefs
A habitat association resting on the standard regional reference works rather than on angling report.
- The Fishes of the British Isles and North-West Europe — Macmillan, 1969 (Reference work)Relied on for: Distribution, habitat association, identification and biology of the fishes and inshore fauna of the British Isles and north-west Europe.States this directlyCitation checked — the work exists and is described correctly
- FAO Species Identification Guides for Fishery Purposes and the FAO Species Catalogues — Food and Agriculture Organization of the United Nations (Scientific institute)Relied on for: Diagnostic characters, family placement, habitat and depth range as set out in the FAO species identification sheets for the region concerned.States this directlyCitation checked — the work exists and is described correctly
Reviewed 2026-08-17. FishingHQ does not state what any rule is or where any rule applies. Where this page says the two species are managed differently, that is a reason to check the authority for the water you are on — not a statement of what it requires.