Onion Trevally - another new record for Sydney Harbour

According to the Australian Faunal Directory, the Onion Trevally occurs in tropical waters from off Exmouth Gulf, Western Australia (22º05´S) to off Newcastle, New South Wales (32º52´S).

For this reason, we were surprised to see John Sear's observation of an individual at Clifton Gardens. This is the first known observation of the species from Sydney Harbour. It's also the 7th time a species has been observed in the harbour for the first time since the 2022 publication of the Sydney Harbour fishes paper by DiBattista and colleagues.

When asked about his observation, John stated, "It was right at the end of my dive. I was heading towards the shore in about 2m of water when I came across three of them. I realised immediately that it was a trevally I wasn't familiar with due to body shape and fin size. With very little air left I only had a few minutes to get a shot and they weren't keen to have their photographs taken. To overcome backscatter in silty water I try to get as close as possible to the subject, but it's easy to overexpose the shot with trevally as strobe light reflects back from the silver body. To fix that I either reduce the strobe output, or point the strobes outwards."

We are delighted that John managed to take such excellent photos despite starting to run out of air and the inherent challenges of photographing trevallies. Thanks John for adding yet another species to the steadily growing Sydney Harbour fish list.

Reference

Joseph D. DiBattista, Tanika C. Shalders, Sally Reader, Amanda Hay, Kerryn Parkinson, Robert J. Williams, Jemina Stuart-Smith and Mark McGrouther, 2022. A comprehensive analysis of all known fishes from Sydney Harbour. Marine Pollution Bulletin 185. pp 1-13. View paper

PS. In different publications the species is sometimes referred to as Carangoides caeruleopinnatus or Turrum coeruleopinnatum.