‘Out on a swim’ is a coral reef blog that tells the stories of the characters who live under the waves and what has caught my eye when ‘out on a swim’ in the lagoons of Norfolk Island. It is also a record of the difficulties Norfolk Island’s reef faces, like many others around the world, as a result of the poor water quality that has been allowed to flow onto it.
This page shows the most recent blog posts. For the complete catalogue, visit the ‘Out on a swim index’ page.
This blog is rated in the Top 20 Coral Reef Blogs in the world.
Sabre squirrelfish, Sargocentron spiniferum, seen at Norfolk Island, increasing its known range southwards by 750 km
A fish once thought to belong only to Norfolk turns up elsewhere; another appears here hundreds of kilometres beyond its known range. Cardinalfishes and a Sabre squirrelfish show how our maps of species distributions are revised.
Read MoreA young Chromis norfolkensis, Norfolk chromis
A Norfolk chromis that turned out not to be Chromis fumea, a blenny found nowhere else, and a tiny goby that may not yet have a name. A look at what we mean by native, endemic, undescribed and newly described – and why scientific names sometimes change.
Read MoreAn aatuti guarding his eggs, Norfolk Island
Aatuti are bold little algae farmers, but how does one of their farms begin? Over the past year, I have been following several coral patches as small white scars became algal footholds, then larger defended patches. I still cannot say what caused the first wounds, but the photo sequences show something fascinating: on a reef where algae is already gaining ground, even tiny changes on the coral surface can become part of a much bigger story.
Read MoreBluespine unicornfish, Naso unicornis. Note the two scalpels at the base of its tail. These fish have been found to live to at least 50 years old. Norfolk Island
Surgeonfish are named for the sharp little scalpels near their tails, but on Norfolk’s reef their more useful work happens at the other end. Pencil surgeonfish, bluespine unicornfish and their relatives help browse algae across the reef – a small daily job that becomes very valuable on an algae-rich lagoon reef like ours.
Read MoreJames Stuart’s three-striped butterflyfish, Chaetodon tricinctus. Image courtesy of the Mitchell Library, State Library of New South Wales; PXD 134
Norfolk Island’s fish fauna reflects both connection and isolation. Some species may arrive from elsewhere as drifting larvae, some populations appear to persist locally, and some fishes known from islands on either side of Norfolk have still not been recorded here. This post looks at what old survey work, regional checklists and genetic studies suggest about that more complicated picture.
Read MoreEclipse butterflyfish – Chaetodon bennetti, Norfolk Island
September is Biodiversity Month – the perfect time to celebrate the astonishing variety of life on Norfolk Island’s reef. From new fish sightings to coral mosaics, every observation is a reminder of how much there is still to learn and protect.
Read more about why biodiversity matters, globally and right here in our lagoon.
Read MoreMr Lemonhead, the yellow boxfish (Ostracion cubicus) 8 August 2025, Norfolk Island
Meet Mr Lemonhead – our lagoon’s teeny yellow boxfish with a big design legacy. He inspired a Mercedes Benz concept car, proving how nature is full of surprises. And he shares the lagoon with other critters whose tricks have also shaped real-world inventions.
Read MoreBluebarred Parrotfish – Scarus ghobban, first recorded in Norfolk Island’s lagoons in February 2021
Over five and a half years of snorkelling Norfolk’s lagoon, we’ve documented 23 fish species not previously recorded in this area. Some are local ghosts, others climate migrants. These observations help us understand and protect what makes our reef so special.
Read MoreNepean Island (left) and Phillip Island (right) to the south of Norfolk Island are free of rats. Rat-free seabird rookeries are important for the health of coral reefs.
Not all poop on a reef is bad poop. In fact some kinds of poop can be a reef’s most important invisible engine. Fish poop, bird poop – even poop that gets eaten again by other fish – all of it keeps the ecosystem ticking over in a way that’s nothing short of extraordinary.
Read MoreEchidna nebulosa, snowflake moray, Norfolk Island
How did the snowflake moray get its proper (scientific) name Echidna nebulosa, and what does it have to do with Australia’s famous and iconic marsupial, the echidna? Read on to find out more …
Read MoreGreen moon wrasse, Norfolk Island, 17 July 2024
I’ve been photographing this guy, a green moon wrasse, since 2020, when he was a young adult just transitioning from being a female to a male. Green moon wrasse are said to live five to seven years in the wild, which means that our lovely old friend here could well be classified as an elder. This post is dedicated to this cheeky and inquisitive fish, the boss!
Read MoreMale birdnose wrasse, Gomphosus varius, Norfolk Island
All birdnose wrasses are born female but will change to males if the conditions are right. Its appearance changes radically throughout is lifecycle, from when it is a juvenile, through to being a female and then finally to being a male (known as sexual metamorphosis, or sequential hermaphroditism). For about three weeks you can see that transition taking place in the sequence of photos in this blog.
Read MoreBlue-barred parrotfish (Scarus ghobban), last seen in September 2021
In my ‘Year in review for 2023 on Norfolk Island’s reef’, published in December 2023, I made a few observations about the apparent disappearance of some fish species from Norfolk Island’s lagoons. I thought I would revisit these, principally because since December there has been so much additional fish activity here, with some exciting population increases and a few new species turning up.
Read MoreGreen moon wrasse, Emily Bay, Norfolk Island
Do fish have eyes that move independently? Well, no, not really, but, yes, sort of, in some species, sometimes!
Read on for a brief ‘Fish eyes 101’ summary of how they work.
Read MoreNorfolk Island’s inshore reef during low tide and at sunrise
Sadly, the year didn’t bring any obvious improvements to Norfolk Island's reef in terms of reductions in incidences of coral disease, or runaway algal growth. And while some fish seem to have departed the scene, another species has re-established its home. Here’s a rundown of what I've been doing during the last four years of observations, and what I've seen happening on our reef in 2023.
Read MoreA small school of scissortail sergeants with one interloper, an Indo-Pacific sergeant, Norfolk Island
There are a few fish species in Norfolk Island’s bays that are easily mixed up. Here’s four commonly confused pairs, with a few pointers to help you identify them.
Read MoreBlack Blenny, Enchelyurus ater found in Slaughter Bay, Norfolk Island
This is a copy of the Australian Fishes journal post about new fish sightings on Norfolk Island: ‘This observation [of a black blenny] highlights the power of citizen scientists working with professional ichthyologists to achieve important outcomes,’ Mark McGrouther, Senior Fellow at the Australian Museum.
Read MoreEmily Bay, Norfolk Island, #thecoloursarereal!
Looking across Emily Bay, do you wonder what is beneath the waves in there? Although this is not strictly part of Norfolk Island’s reef, it is part of one continuous ecosystem; therefore, in today’s March focus on Norfolk Island’s reef I thought it was worth showing you what you can see at your feet as you wade into the shallows.
Read MoreThreadfin butterflyfish, Chaetodon auriga, Norfolk Island
Butterflyfish are flighty, brightly coloured and beautifully conspicuous on our coral reef in their bright yellows and oranges, white and black livery. On Norfolk Island we regularly see fourteen species, just a small portion of the more than 100 species, globally. Large numbers of butterflyfish are a good sign of a healthy reef.
Read MoreYellowstripe goatfish, Mulloidichthys flavolineatus
If you go for a snorkel on Norfolk Island’s reef, one family of fish that you are bound to see is members of the goatfish family. I have seen have six different species inside our lagoons. You can see them all here.
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