Butterfly, flutterbyfish — Norfolk Island's Reef

Out on A Swim

‘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.

DAY 17 – MARCH FOCUS ON NORFOLK ISLAND’S REEF

We shouldn’t have favourites, but if I am asked the raccoon butterflyfish would have to be mine

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.

They are generally quite territorial. Some species will often form a pair bond, which can last for life, and will lay claim to a patch of coral reef as their territory. Having said that, I have noticed others, such as the chevron, citron, and dot-and-dash butterflyfish, are often solitary.

At certain times of the year, usually when the corals are spawning, they will come together to form small schools. It was at coral spawning time that I took the photograph of the threadfin butterflyfish school, top.

Some species feed on corals and only corals, while others will consume plankton as well, but of all the fish that live on coral reefs, and there are thousands, only around 40 species like to crunch on hard coral and more than half of those are butterflyfish. Large numbers of butterflyfish are a good sign of a healthy reef.

The most common species on Norfolk Island’s reef is the threadfin butterflyfish and the least common are the dot-and-dash and the citron butterflyfishes.

Whatever the species, though, I get a real thrill when I get a nice clear photo of these delightful little fish.

Below are photos of our butterflyfish species found here on Norfolk Island. You can find many more images of butterflyfish at different stages of their lifecycle on the fishes page of this website. Scroll down to B for butterflyfish.

Black butterflyfish - Chaetodon flavirostris

Blackback butterflyfish - Chaetodon melannotus

Bluespot butterflyfish - Chaetodon plebeius

Chevron butterflyfish - Chaetodon trifascialis

Citron butterflyfish - Chaetodon citrinellus

Dot-and-dash Butterflyfish - Chaetodon pelewensis

Doublesaddle butterflyfish - Chaetodon ulietensis

Lined butterflyfish - Chaetodon lineolatus

Masked bannerfish - Heniochus monoceros

Oval-spot butterflyfish - Chaetodon speculum

Pinstriped butterflyfish - Chaetodon lunulatus

Raccoon butterflyfish - Chaetodon lunula

Threadfin butterflyfish - Chaetodon auriga

Three-striped butterflyfish - Chaetodon tricinctus

Vagabond butterflyfish - Chaetodon vagabundus

September 6, 2026

Watching El Niño from Norfolk Island

El Niño is strengthening across the Pacific, but that does not tell us exactly what the coming months will bring to Norfolk Island. After a long wet spell, I am watching our rainfall and water supplies more closely again – and, underwater, keeping an eye on sea temperature, algae, coral recruits and the fish that turn up on the reef.

September 2, 2026

What the world’s reefs are telling Norfolk Island

Two major new coral reef reports carry a clear message for Norfolk Island: reefs can recover when pressures ease, but the time available for recovery is shrinking. Norfolk Islanders were raising concerns about water quality, runoff and the health of Emily and Slaughter Bays nearly forty years ago. Today we have much better science, a changing climate and a far clearer understanding of how closely the catchment and reef are connected. This article looks at what that means for water quality, long-term monitoring, dredging and how we manage Kingston from land to sea.

August 25, 2026

When the map changes

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.

August 24, 2026

Endemic, native, undescribed – what do these words actually mean?

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.

August 16, 2026

What’s grazing in the green stuff?

A proliferation of Bryopsis on the reef has brought some beautiful little underwater grazers with it. I follow the trail from sap-sucking sea slugs and egg masses to a bigger question – why is there so much Bryopsis around at the moment?

August 8, 2026

The clam beneath Emily Bay

I’ve seen the beautiful shells of Laciolina chloroleuca in Emily Bay for decades, but I’d never really stopped to wonder where the living animals were. It turns out they may be buried half a metre beneath the sand. A closer look at an easily overlooked clam, its extraordinary shell markings, and the hidden life beneath our lagoon.

August 1, 2026

Reflections of an accidental marine scientist

What I thought would be a steady plod towards retirement, with plenty of time spent nursing grandchildren, was abruptly upended exactly six years ago today. This is the story of how an environmental catastrophe changed the course of my life – and led me to reinvent myself. It is a reflection on how, and why, I became an accidental marine scientist.

July 24, 2026

From ridge to reef: unpicking the Waterway and Wetland Strategy

Norfolk Island’s draft Waterway and Wetland Strategy will guide work for the next ten years. I support its intent, but it needs to be clear, practical and measurable – joining the dots from ridge to reef so we know whether public money is improving water quality and helping the reef.

July 13, 2026

Reef reality in pictures

Let the pictures do the talking. This is the reality on Norfolk Island’s reef today, laid out in a two-minute video.

June 28, 2026

The red seaweed behind low-methane beef

A small red seaweed on Norfolk’s reef has become part of a much bigger story. Asparagopsis taxiformis can look like a delicate red feather duster or, at another stage of its life cycle, like a tiny cottony pom-pom. It is beautiful, easily overlooked, and now being used in the cattle industry to help reduce methane emissions. This post looks at the reef oddity behind the low-methane beef story – and why repeated local observation can be more useful than it first appears.