Some intertidal fish species
To ID fish is an ongoing challenge for Shoresearchers. Many look alike even when you find them sitting under rocks and still.
Some fish’s ecologies can help with ID, but here we introduce some fish which are easier to decipher when seen (even if only glimpses).
Knowing what’s there, especially when it comes to fish ID, helps when you see if first time. So, doing some reading of intertidal fish species would be a valuable additional activity to do in addition to the basic Shoresearch training.
The species in focus are:
tompot blenny/twmpot (Parablennius gattorugine)
butterfish/llyfrothen (Pholis gunnellus)
pipefish sp./pibell fôr (e.g. Syngnathus acus)
long-spined sea scorpion/scorpion môr (Taurulus bubalis)
clingfish/glynnwr (e.g. Lepidogaster lepidogaster)
Montagu’s sea snail/iâr fôr Montagu (Liparis montagui)
You will see what features to pay attention to, which will help lead to an ID of species or species group.
You will then be tested.
Many fish look like others and this is mostly due to the fact you often only get a glimpse, but also many features which can be used to lead to an ID can be hidden in some way if the full view of them is out of water (as is commonly the case). As with other difficult groups, prepare to collect as much information on what you see when you do.
Of the fish chosen, many have similarities with other species, but some are less likely seen due to where they’re found etc. Tompot blennies can look like other blenny species, especially when found out of water and the characteristic “antlers” are less obvious.
1. the tompot, if seen underwater, has tentacles on top of its head which look like antlers, compared to a triangular flap, called a crest of the Montagu’s blenny (another intertidal fish)
2. the dorsal fin of the tompot blenny is long and doesn’t have the clear dip in the middle as the shanny and Mnotagu’s blenny do.
3. compared to most other blennies, the tompot’s body is stout.
4. the tompot blenny can be quite inquisitive/territorial of their patch, but you might also see the others wanting to maintain their patch if they have eggs to guard.
The movers
tompot blenny/twmpot (Parablennius gattorugine)
©Allan Rowat and Ann Wake
- as with all blennies, this fish has a large head, thick lips turned down at the sides and large eyes
- a large blenny-type fish, it can grow to be up to 30cm long, but commonly up to 20cm
- the key feature when seen in water is its antler-type, branched tentacles on top of its head between the eyes
- also, under water, another feature is a dorsal fin extending from the head right to the tail with no clear dip in the middle
- these are commonly mottled brown-red with stripes of darker blotches against pale ones vertically down the back
- this is a stout blenny and likes to guard its crevice/patch. It can be regarded as inquisitive, as it may come out to inspect/shoo away potential predators.
butterfish/llyfrothen (Pholis gunnellus)
©North Wales Wildlife Trust
- a long fish, it can grow up to 25cm
flattened from side to side - down-turned thick lipped mouth and large eyes, like blennies
- has a dark coloured stripe on its head running vertically down over the eye area
- commonly found under rocks on low shore
- clear dark spots circled in paler colour can be seen high on its dorsal edge.
pipefish sp./pibell fôr (e.g. Syngnathus acus) 
©Molly Jones
- extremely long fish (there are 6 species report in Welsh waters, but perhaps only 4 possible as intertidal finds)
- a relative of the seahorse, it has a similar-shaped head (to ID species take note of length of snout in relation to rest of head and depth of snout)
- take note, also of length and girth, as this can help with ID.
long-spined sea scorpion/scorpion môr (Taurulus bubalis)
©North Wales Wildlife Trust
- a fish with a huge, spiny head and are flattened dorso-ventrally (back to belly)
- relatively large intertidal fish growing to 20cm long
- large eyes towards top of head
- backward-pointing spines along gill covers at side of head
- two dorsal fins the first has spines
barbels (a fleshy protrusion, often used as a sensor in fish) at mouth corners and spines in cheeks - colour-matched commonly to substrate and will remain still.
The clingers
clingfish/glynnwr (e.g. Lepidogaster candolii)
©Paul Naylor wwww.marinephoto.co.uk
- a set of species, take care to note size, patterning for help to get closer to species
- these fish are small (6-8cm), flattened (dorsal-ventral) fish often clinging, stationary to the sides or underneath of rocks and can be overlooked
- has a long, triangular-shaped head
has a sucker formed by fused pectoral fins and uses it to suction onto rocks
although there is confusion with which one, one species has blue spots on the top of the body behind the head - can be different colours and patterning.
montagu’s sea snail/iâr fôr Montagu (Liparis montagui)
©North Wales Wildlife Trust
- a small slimy-looking fish
large, rounded head with tapering tail, look tadpole-like - has a characteristic curled way of sitting on rocks (they have a sucker formed from the pelvic fins to attached to the rock)
- found around rocks and algae on the low shore
- grows to about 6cm
- NB other similar fish species (another sea snail species not commonly found intertidally, but also young lumpsuckers which may be).
Alternative factoids
Fish in the intertidal area are fascinating and need to be some sort of specialist if they’re spending most of their lives there. Here’s a bit more about these special fish.
Many fish species which live in the intertidal area can live out of water for a period of time (under seaweed or in crevices where moisture is maintained)
The tompot blenny can be identified by the unique patterned of spots on its face and one rock in Devon has been studied and all the tompots, with their stable territories have been named by Paul Naylor.
Clingfish lack scales and instead are covered by a protective mucus.
The sea scorpion is not the same fish as scorpion fish which is a name used for a number of species including the lionfish – a virulent invader, this fish is a threat to marine ecosystems outside its native range. It has been found in UK waters recently.
The next section is the quiz. Click to begin the quiz, the questions will appear below. If you get any one question wrong within each quiz page, the you will be marked as wrong for the whole page. Answers will appear one you’ve finished each question.
You will be tested on what you’ve learnt so far using the reading and video info. Don’t worry too much, as once you’ve been out on the shore, the ID features you’ve learnt about will make more sense and after a couple of visits you should feel more confident about your ID.
Good luck!