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Articles reproduced here come from past Rottnest Society Newsletters and other documents up to 2005.

Western Buffalo Bream, Kyphosus cornelii - this is a brief report from our Newsletter archives on a fascinating talk given to members and friends by Dr. Paddy Berry in 2002.

There are two different species of Buffalo Bream found in the waters surrounding Rottnest Island. Common Buffalo Bream is frequently seen feeding on brown algae, with its tail out of the water. The tail has a black margin, and the fish also has a moustache. Its endemic relative, Western Buffalo Bream, Kyphosus cornelii, lacks the black colourations and feeds upon red algae.

 Western Buffalo Bream ranges from Cape Leeuwin to Shark Bay, with a large population in the Abrolhos. There is an influx of numbers around Rottnest when the Leeuwin Current runs during winter. These fish are responsible for the polygonal shapes on the reef platforms along the southwestern coast of the island. Each inner area is a territory, separated from others by ‘hedgerows’ of brown algae. There is a high amount of biomass in this habitat, with algal growth high due to abundance of light.

 Each border is patrolled by territory holders, and these fish tend to the algal bed. Roving groups of bream challenge for the claim, but territory is vigorously defended and most often individuals within the group only manage to snatch a mouthful or two before they are chased away. It is estimated that territory holders spend 20% of their time defending; the rest is spent on managing the turf.

The fish maintain their positions until the last possible moment, and stay on the platform until the water is about 18 inches deep. They then pass the time in caves and underhangs until the platform is submerged again. Territory holders have been found to be regulars – a marked fish was recorded as holding the same territory for 23 months. These fish are the most successful breeders as they have a plentiful supply of nutrition.

There is no attempt by territory holders to obtain adjacent claims and expand their domain. The arrangement of the polygons has been mathematically shown to give the maximum volume to surface area ratio. The fish have a minimum border to defend. The hexagonal pattern can be described as the morphing of overlapping circles, and is readily displayed in nature.