‘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 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 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 MoreSmall numbers of different fish species is not an unusual phenomenon on Norfolk Island’s reef, but it does demonstrate what a tiny, precious, coral reef ecosystem we have, when we can count individuals on one hand and watch each of them grow, like these little blackeye thicklips, a member of the wrasse family.
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 MoreA territorial banded scalyfin, Parma polylepis (aatuti), Norfolk Island
The banded scalyfins and the multispine damselfish are arguably two of the most common species in Norfolk Island’s lagoons. People often confuse them, particularly the juveniles, so here are some photos to clarify which are which. Once the differences have been pointed out, you’ll never confuse them again.
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 MoreOne of the pair of ‘sometimes’ resident snubnose darts, Norfolk Island
Norfolk Island’s reef is small and intimate. We can count the numbers of some species of fish on one hand, and that is how I can watch the comings and goings with interest as I swim among them. I love the stories that play out and which I get to witness – these snubnose darts (Trachinotus blochii) are a case in point.
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.
Read MoreAdult female elegant wrasse, Norfolk Island
It’s always fascinating to see how fish change in appearance as they mature. Today’s blog post features the elegant wrasse, Anampses elegans. But not only do they change how they look, they also change how they socialise and move about the reef.
Read MoreNorfolk Island blenny, Parablennius serratolineatus
It is fascinating to me that, in terms of biodiversity, there is still a slight feel of the frontier to Norfolk Island. So remote and isolated from any other land mass, it stands to reason that we have some different species that are found only here. On such is the Norfolk Island blenny.
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