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Rottnest Marine Life
An Identification Guide for Snorkellers and Divers
Fish you're almost guaranteed to see on every dive and snorkel:
Silver Drummer and Western Buffalo Bream
These simple, grey fishy-looking fish are absolutely everywhere around Rotto! They're usually the first fish you'll notice on a snorkel, because they often form schools in the sandy shallows.
There are two different types of buffalo bream at Rotto, both very similar in appearance and sometimes hard to tell apart.
The Western Buffalo Bream, Kyphosus cornelii is silvery grey all over, though with a slightly darker tail.
The Common Buffalo Bream Kyphosus sydneyanus (also known as the Silver Drummer) looks almost the same, but with a thick black line at the edge of its tail, black fins and a moustachioed appearance.
The Western Buffalo Bream is by far the most common in shallow inshore areas, but in deeper waters you'll often see a massive school of Silver Drummers.
A small school of Western Buffalo Bream:
A lone silver drummer at Dyer Island:
Perhaps the second-most likely-to-see fish at Rottnest is the Scalyfin, a darkly coloured damselfish. They are loners and hang close to the weedy reef, guarding their patch. If you get up close to one, it will turn towards you and spread its fins, no doubt trying to scare you away.
Depending on the lighting, sex and life-stage, adult scalyfins appear black, dark brown, dark blue-grey or dull browny-yellowish-green. They have a squarish blocky shape and a rounded forked tail.
The juveniles are a similar shape to the adults, only smaller. The colouration is bright orange/yellow with a few thin white stripes and a smattering of irridescent blue spots. Juvenile scalyfins aren't commonly seen at Rottnest, but if you're lucky enough to see one, it will really stand out!
By far the most common variety of scalyfin at Rottnest is the McCulloch's Scalyfin, but it's also possible to spot a Western Scalyfin, which has a slightly protruding mouth (compared to the McCulloch's).
A scalyfin on a shallow weedy reef next to Dyer Island:
A defensive scalyfin, also taken at Dyer Island:
Western King Wrasse
Another very common Rottnest fish is the Western King Wrasse. These fish have a highly variable appearance depending on whether its male or female, and the stage of life its at.
The adult males are larger and brightly coloured. The quickest way to recognise them is to look for either dark pink cheeks, or a bright pink all-over colouration. Also look for a vertical white band behind the pectoral fins. The colour on the rest of his body can range bright dark pink and white, to white or pale grey with darker splotches.
Females adults are slender, coloured white with a horizontal red stripe from the eye to the tail. They often swim around in groups.
Male Western King Wrasse:
And another male western king wrasse colouration:
Female Western King Wrasse:
Red Lipped Morwong
Red lipped morwong are a fairly big fish seen absolutely everywhere in the waters around the island (and off the mainland, too). You'll see them on almost every snorkel, swimming around the shallow reefs and lying motionless under ledges. They tend to be solitary, but sometimes hang around in pairs.
They're instantly recognisable by their spotty and banded pattern, and big bright red lips. From afar, the colouration appears to be pale yellow with diagonally vertical dark bands, but look closer and you'll see the bands are made up of dark brown spots close together, with more spots further apart on the paler areas. The head, tail and dorsal fin have a more obvious polka-dot pattern.
Red Lipped Morwong at Salmon Bay:
Two of them under a shallow ledge at Mary Cove:
More Rottnest fish:
These fish seem to constantly be eating, scavenging the reef or seafloor.
The base colour is white to very pale yellow, but in the light they have a flourescent blue sheen. The top and underside are pinkish. Orangey-brown stripes run horizontally from head to tail, and at the base of the tail is a big black spot.
Like all goatfish, they have two sensory whiskers on their face.
Footballer Sweep are small oval shaped fish. They're white with diagonal yellow stripes (with dark borders edging the stripes), and yellow fins and tail.
They're frequently seen in big schools around the reefs at Rottnest, Perth and elsewhere in the South West.
Banded Sweep are an oval-shaped fish with pointy fins giving them a triangular-look. The colour is a silvery brownish-grey with two thick vertical black bands. They appear to have a stern, fierce expression.
Juveniles are more browny-gold with less obvious bands.
Banded Sweep are pretty common, but you'll usually see just one per dive because they don't form schools. You tend to see them more in deeper areas, over seagrass beds and around kelp-covered reefs.
Banded Sweep off Dyer Island:
Banded Sweep at Armstrong Point:
Small bright yellow damselfish with horizontal (slightly slanted) black stripes. They're one of the most frequently seen fish around Perth, and are also common at Rottnest.
There are two types of moon wrasses, both of which are commonly seen on the south side of Rottnest and around the west end. These are the Green Moon Wrasse, Thalassoma lutescens and the Moon Wrasse, Thalassoma lunare (also known as the Lunar Wrasse). Both species have crescent-shaped tail edges, from which they get their names.
At first glance the moon wrasse looks identical to the green moon wrasse, but once you know a few key differences, they're easy enough to tell apart. Both are beautiful, brightly-coloured fish, with a similar blue/green base colour and pattern on the head. The most obvious differences are in the tail and pectoral fins.
A moon wrasse (lunar wrasse) next to pocillopora coral in Little Salmon Bay:
A green moon wrasse in the eastern corner of Salmon Bay:
These are fairly common on the south side of the island. They are small damselfish, coloured white (sometimes with a hint of yellow) with 5 vertical black stripes. They get their name from the scissor shape of the tail, which is further emphasised by 2 more black stripes following the lines of the tail. They usually swim around in groups of two or more.
More shy and retiring than its close relative the red-lipped morwong, the dusky morwong is a big grey fish with a subtle splotchy banded pattern. It has the typical grumpy-looking morwong face. They tend to lie motionless on the seafloor, often in the dark under an overhang.
A dusky morwong in the eastern corner of Salmon Bay, near the offshore rock:
Next to Armstrong Point:
A tropical species sometimes seen on the south side of the island. The top half of the fish is yellow and the bottom half white, with 6 thin black vertical stripes, including one through the eye and one at the base of the tail.
Convict Surgeonfish at Parker Point:
Wobbegongs are the most frequently seen shark at Rottnest. They're easily recognisable with their flat body and mottled camouflage pattern of brown and yellowish spots, stripes and splotches. They get their name from protruberances around the chin. "Wobbegong" means "shaggy beard" in an Aboriginal language.
Wobbegongs will try and bite you if you provoke them - even by accidentally touching one - but are harmless if you leave them alone.
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Thrombolites, Yalgorup Lakes
The Thrombolites are south of Mandurah, a day-trip from Perth.