Fishes of the intertidal rocky shore

identifying intertidal fishes in New Zealand

By Dr J Floor Anthoni (2007)
Rock pool fishes are best identified from pictures. This page covers the most commonly encountered intertidal fishes in New Zealand, ranging from visitors to permanent inhabitants of the intertidal rocky shore. New Zealand has many species of triplefin, and these often look very similar.
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Fishes have internal skeletons and all those found on the rocky shore have bony skeletons, unlike the cartilageous bones of sharks and rays. Living in a wave-washed environment is taxing unless one is small and one can hold oneself firmly in place. Triplefins do this by means of extended breast fins (pectorals), the rockfish by its rubbery back fin (dorsal) and clingfish by their modified hip fins (pelvic).
Fishes are easy to identify once they show themselves, one would think. But many species have a range of costumes (variable colour patterns), which makes them very difficult to tell apart. 

spotty (Crenilabrus celidotus)
f039805: in order to be able to live on the rocky shore, fish need to be really small. So only the young of common fishes can be found here, such as young spotties (Crenilabrus celidotus). Spotties are born female, so it highly unlikely to find male spotties in a rock pool. In the background a variable triplefin.
a very young sweep (Scorpis lineolatus)
f036907: a very young sweep (Scorpis lineolatus) is silver coloured with red specks on its side and a green back as it settles out from its planktonic babyhood. It is commonly found underneath overhangs in rock pools, in spring/summer.
olive rockfish Acanthoclinus fuscus
0609149: the olive rockfish (Acanthoclinus fuscus) is easily identified from its eel-like shape and long back fin with bent-back, rubbery, finrays. It also often has a white stripe over its snout, but can also discolour itself to jet black. The rockfish can live for hours out of the water, which helps it to guard its nest of pink eggs under a stone, high up the intertidal. The rockfish can grow to 30cm in length. Several species are known in NZ, but only this one is common on the rocky shore. It is a predator, feeding on small crabs, shrimps, sea lice and slaters.
Young lumpfish Trachelochismus pinnulatus
f050430: a 30mm young lumpfish (Trachelochismus pinnulatus) is because of its neck patch, difficult to see, even though they may be quite common. Taking this photo took much patience.
mature lumpfish Trachelochismus pinnulatus
f050604: A mature lumpfish (Trachelochismus pinnulatus) has a blunt snout, coloured body (yellow, green, brown, reddish) with longitudinal stripes and spots on its head. It can grow to 100mm length.
tiny eggs of lumpfish Trachelochismus pinnulatus
f050622: the lumpfish lays its eggs upside down under a stable rock. First these look red (on left), but soon turn transparent with two blue eyes peeping through (on right). The eggs are laid neatly and equally spaced.
closeup of clingfish suction disc
05062206: closeup of clingfish suction disc of a lumpfish stuck to an aquarium window shows the large breastfin (pectoral) and modified hipfins (pelvic).
the urchin clingfish (Dellichthys morelandi)
f040429: the urchin clingfish (Dellichthys morelandi), as its name suggests, is often found underneath sea urchins where also bugs of all kind shelter. With its slender form and pointed snout, the urchin clingfish manages to snatch these bugs from inbetween a forest of spines and suckerfeet.
crested blenny (Parablennius laticlavius)
f051707: the crested blenny (Parablennius laticlavius) is club-shaped with a large blunt head and slender body with a black stripe. It has only one long backfin. These 'slimefish' do not have scales and can live to a ripe old age.  They are also rather swift and smart, and are therefore difficult to catch or to photograph. 
crested blenny (Parablennius laticlavius)
f032803: the crested blenny (Parablennius laticlavius) is a shy little fish, easily recognised by its thin black stripes and a crest over each eye. The crested blenny seeks out a snug fitting hole in which it can withdraw itself entirely. From this position it can maintain a cleaning station visited by fish who want their nits (sea lice) picked off.


common triplefin (Fosterygion lapillum)
f050618: the common or pebble triplefin (Fosterygion lapillum) begins its life in this striped costume, looking a bit like a crested blenny with its two black stripes. The fish shown here is only 25mm long, and is easily overlooked in rock pools, and when it moves, it is so fast that it is often not noticed. (L: lapillum= pebble)
common triplefin (Fosterygion lapillum)
f034129: common triplefin (Fosterygion lapillum) or cobble triplefin in a light costume.
common triplefin (Fosterygion lapillum)
f049623: the common triplefin can also colour its back fin red, and its entire body between white to yellowish to olive to black.
common triplefin (Fosterygion lapillum)
f033705: when spawning, the common triplefin becomes entirely black with a bright white margin on its anal fin.
variable triplefin (Fosterygion varium)
f032212: the variable triplefin (Fosterygion varium) has many costumes but never a black line. Its snout is often red. It has a relatively large mouth.
variable triplefin (Fosterygion varium)
f034125: the variable triplefin in one of its light suits. It can also look like the common tyriplefin in any of its dark suits, but it is almost twice as large.
speckled triplefin (Grahamina capito)
f033737: the speckled triplefin (Grahamina capito) has many speckles over its entire body which is usually evenly coloured. It also often has a red backfin.
speckled triplefin (Grahamina capito)
f050615: speckled triplefin in a light suit. Speckled triplefins are much less common than variable triplefins.
spectacled triplefin (Ruanoho whero)
f033700: the spectacled triplefin (Ruanoho whero) is easy to recognise from its dark eyes joined by a dark band, as if it were wearing 'shades'. But it too has many costumes. This is a shy fish, usually living underneath safe rocks.
spectacled triplefin (Ruanoho whero)
f033707: in its spawning costume, the spectacled triplefin loses its spectacles.
mottled twister (Bellapiscis lesleyae)
f034609: the mottled twister  (Bellapiscis lesleyae) or rockpool triplefin is a small fish with mottled olive-green colour, blunt snout, thick lips and large breast fins. It is named after its zig-zag  side band. It does not seem to assume various costumes.
cryptic triplefin (Cryptichthys jojettae)
f034521: the cryptic triplefin (Cryptichthys jojettae) lives in the most turbulent of waters, often resting on the sheltered sides of rocks. As its name suggests, it is hard to see. It too has various costumes.
f035602: the robust triplefin (Fosterygion robustum) is easily confused with the common triplefin, but it lacks the horizontal stripe and is black-speckled all over. It is more common around the South Island.
f034516: unidentified triplefin, 40mm.