The curious case of the peacock damselfish

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 7 – March focus on Norfolk Island’s reef

Juvenile peacock damselfish, *Pomacentrus pavo*, February 2021

Today in my March focus on the coral reef of Norfolk Island I am featuring a fish called the peacock damselfish – Pomacentrus pavo. They are a delicate little fish, a gorgeous neon blue with a pale lemon-tipped tail, which only grow to 8.5 or 9 cm. It can be distinguished from similar fish (such as the neon damsel) by the tiny dark ‘ear’ spot near its gill cover.

I’m rather curious about this guy’s life cycle. Our inshore reef – from Emily Bay to Slaughter Bay – is small, so it’s relatively easy to get to know what is in there. Often you can count the fish of a particular species on one hand, and the peacock damselfish is a perfect example of this.

Because I have been only looking at three individuals, it is interesting to notice how their colours change throughout the year (see the images below). Or maybe it is a trick of the light. Certainly, they seem to lighten up from October through to February.

For ages we had just one that I would see regularly hugging a large bommie in Emily, often on the shady side. I never saw any others of his kind, until one day I saw five babies near a small inshore rock, quite some distance from the original bommie. So clearly there must have been a few others around. That was in February 2021. These babies seemed to disperse across the Emily Bay and channel area that runs between the two bays. At first, I could find four of them, then one disappeared and we were left with just three. For the next 18 months or so I would stop by and observe these three individuals, all living quite distant from each other in a solo existence on their respective coral bommies.

I usually find them midway up the side of a reef wall, although when the coral spawns they get a little more daring and will swim happily around just above the reef, presumably snacking on the coral spawn like the other damsel species.

The curious thing is, that almost overnight at the very end of December, all three of these fish disappeared. Did a message get passed across the water column for them to meet up for breeding? And if so, how? Will they come back? Will there be more babies? I always seem to have so many questions and so few answers!

This year, juvenile fish for any of the species in our bays have been hard to find and I have no idea why. Maybe they are later this year? Maybe the influx of freshwater has driven them out beyond the confines of the lagoons. Our last baby peacock damselfishes appeared in mid-February (2021), so I confess that I had expected to see some by now. I’ll keep looking!

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.

June 20, 2026

From coral scar to aatuti farm

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.

June 15, 2026

Norfolk’s water quality – when action is reported as outcome

A recent Australian Government media release presents investment, monitoring and catchment works as progress on Norfolk Island’s water quality. Some of that work is useful, and some of it was badly needed. But activity is not the same as proven improvement. This post looks at Kingston sewerage, wetlands, cattle, acid sulfate soils, groundwater and reef health, and asks whether Emily Bay and Slaughter Bay are actually being better protected.

June 14, 2026

How surgeonfishes got their name

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.

May 28, 2026

A shrimp storm

While setting my research cams last week, I swam into what looked like an underwater snowstorm. It appeared to be the aftermath of a mass moulting event, with large numbers of tiny, translucent shrimp-like exoskeletons drifting together near the surface.

Kingston dredging: what happens when a reef does not fit the framework

This correspondence with DCCEEW is about more than one dredging proposal. It is about what happens when an ecologically distinctive place is assessed through standard tools that do not always make its most important values easy to see. I am publishing it here because that is something we need to be aware of, both on Norfolk Island and more broadly in Australia.

May 24, 2026

Kingston dredging: the project advances, the questions remain

Kingston dredging is edging closer, and the paper trail is growing. This post brings together earlier correspondence with the Department and the latest media release so readers can see what has been asked, what has been answered, and what still remains unclear about the project, its rationale, and the protections proposed for the reef.

May 17, 2026

The lime-green coral in Slaughter Bay – a 40-year paper trail

Green Mountain – the name I give this coral in my database – is a coral I’ve photographed for years as I swim past. Then I found its backstory in the Norfolk Island National Parks archives: a rough map, reused paper, a note in the margin – ‘still thriving’. That’s how baselines begin.

April 5, 2026

What Norfolk Island’s reef tells us about environmental blind spots

The Kingston dredging proposal on Norfolk Island raises a bigger question than dredging alone: how well do standard environmental assessment tools capture the real significance of a remote and unusual reef system like Norfolk Island’s?

March 30, 2026

Hammer coral time!

Hammer corals have unique tentacles that are large, fleshy, and tubular; these terminate in a ‘T’-shaped, hammer-head or anchor. Beneath all these softly waving tentacles is an extraordinary skeleton structure, which helps define them as a large polyp stony coral.