Scalloped Ribbonfish in Cabbage Tree Bay

This is the 180th Australasian Fishes Project journal post since the project's inception in 2016.

Those journal posts have covered a range of topics including new records for Sydney Harbor, new distributional range extensions and member profiles. This post doesn't fit into any of those categories. Instead, it just features an amazing fish and I thought it worth sharing with everybody.

The fish is a Scalloped Ribbonfish, Zu cristatus. The species occurs off northwestern Western Australia and down most of the east coast to Tasmania (view distribution).

This observation, which was made by Peter Barfod (@fiftygrit), is the 4th of the species for the Australasian Fishes Project, but the first of a live fish showing its spectacular fins.

Peters stated, "I often swim at Cabbage Tree Bay and always take a camera. I have seen some rare critters there and this may have been the rarest. Whilst swimming, I saw people grouping and looking in the water and anticipating that they saw something interesting, I approached and did not see anything but floating seaweed. I asked what they saw and they said look again. It took me a a few seconds to refocus but as soon as I saw it, I suspected it was some sort of oar fish because its orientation was vertical in the water. Out came my camera and I snapped away. It did not move. Was it alive? Surely it would go deep with the 4 people around it. Looking very carefully, I could see the dorsal fin move slightly. This fish was very committed to its camouflage. Afterwards, I knew the fish was special and anticipated loading the observation on iNaturalist.".

Strictly speaking, the Scalloped Ribbonfish (Family Trachipteridae) is not an Oarfish (Family Regalecidae) although both fishes are classified in the order Lampridiformes (view the classification). Fishes in this order show extremes of body form, from the deep-bodied Opah to the Oarfish, the longest of all fishes.