Due to their isolation, several species on the Kermadecs have evolved into unique forms, found only here. Living in a very small spot, surrounded by a very large infertile ocean, poses special requirements, such as:

• growing old: the eggs and larvae of nearly all marine organisms spend some time (days to weeks) as plankton in the open water before settling down (recruitment). Because of ocean currents, the small size of the islands and the large ocean around, recruitment is uncertain and sporadic. Organisms therefore must sustain many years of unsuccessful spawning.
• living frugally: the concentration of nutrients in the water is low, supporting only low densities of plankton and plant growth. In order to survive through all seasons, marine organisms must be able to live thriftily.

The following overview illustrates which fishes one can recognise when diving the Kermadecs:

• endemic species:  caramel drummer (Girella fimbriata), Kermadec scalyfin (grey angelfish) (Parma kermadecensis), Kermadec triplefin (Enneapterygius kermadecensis),
• common both in northern NZ and Kermadecs: Short-tailed stingray (Dasyatis brevicaudata), Eagle ray (Myliobatus tenuicaudatus), grey moray (Gymnothorax nubilus), speckled moray (Gymnothorax obesus), Rock cod (Lotella rhacinus), slender roughy (Optivus elongatus), golden snapper (Centroberyx affinis), [Northern scorpionfish (Scorpaena cardinalis)], half-banded perch (Hypoplectrodes sp.), bluefish (Girella cyanea), blue maomao (Scorpis violaceus), mado (Atypichthys latus), pink maomao (Caprodon longimanus), two-spot demoiselle (Chromis dispilus), Sandager's wrasse (Coris sandageri), green wrasse (Notolabrus inscriptus), orange wrasse (Pseudolabrus luculentus),
• common in the Kermadecs, rare or absent in NZ: Galapagos shark (Carcharhinus galapagensis), spotted moray (Gymnothorax pionodon), mosaic moray (Enchelycore ramosa), northern conger eel (Conger wilsoni), Red lizardfish (Synodus doaki), northern kahawai (Arripis xylabion), red lionfish (Pterois volitans), Cook's scorpionfish (Scorpaena cookii), yellow-banded perch (Acanthistius cinctus), gold-ribbon grouper (Aulacocephalus temmincki), toadstool grouper (Trachypoma macracanthus), spotted black grouper (Epinephelus daemelii), black-spot goatfish (Parupeneus spilurus), bar-tailed goatfish (Upeneus francisi), three-line cardinalfish (Apogon doederleini), bronze bullseye (Pempheris analis),  grey drummer (Kyphosus bigibbus), grey knifefish (Bathystethus cultratus), blue knifefish (Labracoglossa nitida), splendid hawkfish (Cirrhitus splendens), surgefish (Chironemus microlepis), Kermadec demoiselle (Chrysiptera rapanui), Lord Howe coralfish (Amphichaetodon howensis),  striped boarfish (Evistias acutirostris), notch-head marblefish (Aplodactylus etheridgii), painted moki (Cheilodactylus ephippium), rainbowfish (Suezichthys arquatus), mimic blenny (Plagiotremus tapeinosoma), white-dot blenny (Cirripectes alboapicalis),
• rare in the Kermadecs, common in NZ: trevally (Pseudocaranx dentex), kingfish (Seriola lalandi), kahawai (Arripis trutta), goatfish (Upeneichthys lineatus), porae (Nemadactylus douglasii), black angelfish (Parma alboscapularis), red pigfish (Bodianus unimaculatus), crimson cleanerfish (Suezichthys aylingi), crested blenny (Parablennius lacticlavius), leatherjacket (Parika scaber),  clown toado (sharp-nosed puffer) (Canthigaster callisterna),
• rare in Kermadecs, absent or rare in NZ:  masked moki (Cheilodactylus sp.), Pacific gregory (Stegastes fasciolatus), northern splendid perch (Callanthias australis), blue-spotted wrasse (Anampses caeruleopunctatus), ladder wrasse (Thalassoma trilobatum), elegant wrasse (Anampses elegans), combfish (Coris picta), two-tone wrasse (Thalassoma amblycephalum), sunset wrasse (Thalassoma lutescens), tattooed rockskipper (Entomacrodus niuafoouensis), spotted surgeonfish (Prionurus maculatus), morse-code leatherjacket (Thamnaconus analis),

f031228: A young Abbott's moray eel (Gymnothorax eurostus) peeps out from behind the shelter created by a shagpile coral. This coral cloaks the rocky bottom while leaving a living space for others. Young fish and eels enter through an opening like this, and keep it open, much like antarctic seals keep their breathing holes open. On right: f031227: Grey moray eel (Gymnothorax nubilus)

f031227: Grey moray eel (Gymnothorax nubilus) among shagpile coral.

f031203: A Cook's scorpionfish (Scorpaena cookii) is surprised by the photographer's light, looking much different than its surroundings. But by day, in the presence of blue light, it looks very much like the seaweeds around it.

This is what the Cook's scorpionfish looks like by day. For this photo, the red and orange components of the light have been reduced, simulating daylight at 10m depth.

f030916: Toadstool grouper (Trachypoma macracanthus) and a mature Cook's scorpionfish (Scorpaena cookii) sitting side by side. The toadstool grouper actively seeks prey whereas the scorpionfish waits for prey to come near its mouth.

f031122: Toadstool grouper (Trachypoma macracanthus) in its sleeping den. The fish is about to change colour, like pulling its pyjamas on.

f030934: A young yellow banded perch (Acanthistius cinctus) hovers in perfect balance inside its cave. One usually finds several perches living together in the same cave. They form permanent bonds.

f031818: Goldribbon grouper (Aulacocephalus temmincki). These groupers have a bright yellow line running on each side of their backs. The rest of the body changes colour at will. Here it is just changing from bright blue to black.

f031016: Northern kahawai (Arripis xylabion) in schooling formation. This kahawai is endemic to the Kermadecs and must have adapted to the paucity of pelagic food.

In this detail of previous image, it can be seen that the black patterns on the back of the northern kahawai differs from that of the coastal kahawai (Arripis trutta).(not shown)

f031023: These yellow and grey drummers are the same species (Kyphosus bigibbus), but different colour forms. Colour morphs are common in plants, but much less common in animals. Feeding on mat forming algae, they try to avoid being bitten by the numerous mimic blennies.

f031032: Caramel drummers (Girella fimbriata) and grey drummers in stormy water with incessant and strong water movement. Notice the large barnacle formations with matting red algae on the rocks. This fish feeds on small algae, is very shy and endemic.

f031008: Grey knifefish (Bathystethus cultratus) swimming near the surface. These fish are usually found in the most turbulent of waters where suspended bubbles limit visibility. They feed on planktonic organisms. In the background a school of northern kahawai.

An enlargement of a section of previous picture shows its odd knife shape, which is perfect for catching organisms living under and on the surface of the sea. This fish is related to the blue maomao (Scorpis violaceus) found in New Zealand and here.

f031221: The splendid hawkfish (Cirrhitus splendens) is conspicuous by night but well camouflaged by day. it lives in the shallows and is well equipped to hold on firmly to whatever unevenness the rocks may offer. It eats small crustaceans. Notice the brushes at the tips of its dorsal spines, characteristic of hawkfish.

f031129: The painted moki (Cheilodactylus ephippium) is rare in NZ but common at the Kermadecs and Norfolk Island. It is a very beautiful fish with spectacular markings and colours, particularly on its face and tail.

f031126: At dusk, before the dark of night, fishes of all kind come together to the few caves to find shelter for the night. On left a yellow banded perch. In the centre a notch-head marblefish (Aplodactylus etheridgii) and in the rear a few blackspot goatfish (Parupeneus spilurus) , with painted moki hovering above. Out of view above, five lionfish clinging to the wall. Notice how the marblefish is much more brown coloured than the NZ variety.

f030931: Kermadec scalyfin (Parma kermadecensis) or grey angelfish, resembles the black angelfish in shape but not colour. These fish are named scalyfins because their dorsal fin spines have scale patterns in between, which sets them apart from other groups of fishes.

f032002: Lord Howe coralfish (Amphichaetodon howensis) are usually found in pairs. The pair bond lasts for life. These fish are well equipped to pick morsels of food like shrimps from the gaps in between coral heads.

f031207: This Lord Howe coralfish has just bedded down for the night and is in the process of changing it colours.

f031519: Striped boarfish (Evistias acutirostris)

f031510: striped boarfish are often found in small groups in the shelter of caves like this. The roofs of such caves are often richly covered in sessile animal life like gorgonians, zoanthids, featherstars and so on. Notice the masked moki (Cheilodactylus sp.) in the bottom right corner.

f031526: A large fruit bowl coral offers a vast hiding place underneath, happily accepted by these small damselfishes. They also sleep here, which explains why they cannot be found during night dives. The green ones with spots are young two-spot demoiselles (Chromis dispilus), whereas the yellow ones are Easter Island demoiselles (Chrisiptera rapanui). They have beautiful colours and white masks (not clearly visible).

Detail of the bottom right corner.

f031311: In this photo one can see that two-spot demoiselles are very common in some places at the Kermadecs. They prefer promontories with nearby flowing water to catch their planktonic food.

f031313: Blue maomao (Scorpis violaceus) are also common around promontories. Here a dense school of blue maomao and demoiselles accompanies a diver, out of sheer curiosity. Among the blue maomao, often blue knifefish are found, conspicuous by their golden backs (not shown).

f032008: A male orange wrasse (Pseudolabrus luculentus) has changed his colour to bed down for the night. First he sees to it that all his females have burrowed themselves in the coarse sand. Then he follows suit.

f028614: This picture shows the male orange wrasse in daytime colours, when it has its business suit on. Compare it with his pyjamas shown left.

f031235: Female morse-code leatherjacket (Thamnaconus analis) found sleeping near a fruit bowl coral. Rather ill at ease, it has erected its dorsal spine which prevents predators from swallowing it. It derives its name from the dash-dot patterns on its sides, which it can turn off at will, but the blue belly button remains.

f031803: Kingfish (Seriola lalandi). The kingfish around the Kermadecs are few and far between, and they are slender, showing signs of starvation.

Two Galapagos sharks (Carcharhinus galapagensis) patrolling the sandy bottom near Fishing Rock. These sharks are quite inquisitive, and come very near for a close look, which is rather frightening. They have been known to attack people, but here they are rather small and docile. They are typically 1.5m long, and very slender.

Frontal view of the Galapagos shark. The dark spot on its dorsal fin is not typical, but identifies this individual. Galapagos sharks are found over a large area in the southern Pacific Ocean. They resemble small bronze whaler sharks. Both Photos: Lance Kennedy.