Discussion over the ID of the species involved in the recent flounder sighting have continued since the posting of A Flounder Chasing & Eating a Toxic Toadfish.
The observer has stated that they had ID’d it as “Large-tooth(ed) flounder” Pseudorhombus arsius: –
“I identified the flounder using my copy of “Sea fishes of Southern Australia”, but had got the name wrong, adding “ed” to “large-tooth” on the file names. There is also in the book a “short-tooth flounder”, which probably confused me into referring to the fish as a “long-tooth” flounder. …… I didn’t think it was a small-tooth flounder because of the book description for the large-tooth.
“I spent some time attempting to decide which sort of flounder it was as the book describes sizes (which narrowed it down as this one being quite large, taking a picture with my watch next to it for scale), but then also saw the description in the book about the two dark blotches being diagnostic to the large-tooth flounder.
I spent well over an hour photographing and filming the fish (lots of suspended weed and “washing machine” currents) as I was very impressed with its speed of changing depth of colour, fading to match the fine white sands when on this, to immediately darken as entering the darker weedy and reef areas, during which time the two dark blotches would be unquestionably obvious, whereas the blotches become not so obvious when the flounder was blending in with the white sands.
“There this a picture with a close-up of the flounder’s head front on to show it having just one eye, which appears to me as being possibly a result of past injury(?): –
“With my own vision not being what it used to be, it took some time to realise this, as much of the earlier pictures I got as close-ups were on the fish’s left side (no obvious eye), finding that from this side the fish appeared to be largely unaware of me and easily photographed; eventually, as time went on, it got to becoming accustomed of my presence and (it allowed me) more easily taking pictures from either side, with a clear distinctive sharp eye extending from its head on its right side, with colours in the eye setting it apart from the rest of the fish’s monochrome sandy yellow-brown body (at times bright yellow around the throat underneath – this made me realise the left eye was not there*.
* (More crazy theory – maybe some toad fish had attacked it in the past giving rise to the flounder’s aggressiveness towards toadfish, having watched it completely ignore a baby/small goat fish right next to it during this encounter). When I got home and looked at the pictures in the book showing both eyes clearly being present, I came to the assumption the left was lost due to injury perhaps.”
“Sea fishes of Southern Australia” described the two blotches as being diagnostic of the large-tooth flounder” – (“two obvious dark blotches on the body”).
According to https://australian.museum/learn/animals/fishes/largetooth-flounder-pseudorhombus-arsius/, “The species varies in colour, closely matching the substrate it is resting on. It is best separated from other members of its genus by the presence of two dark spots placed centrally on its dorsal surface. The first is located just behind the pectoral fin, the second is halfway between the first spot and the tail fin.”
A head-shot featured at https://australian.museum/learn/animals/fishes/largetooth-flounder-pseudorhombus-arsius/ looks very similar to this recent photo: –
When posting A Flounder Chasing & Eating a Toxic Toadfish, I had forgotten that I had glanced at “Swainston’s Fishes of Australia” from our library: –
Just for reference, here are photos of the pages on sand flounder: –
