hi dan. the differences between the 2 species can be fairly similar in some cases as we mis identified a brave few in our first year of fishing for them. i have loads of refrence books at home with conflicting ideas about how to tell them apart. but when you know what to look for they are pretty easily told apart. some books telly you to look for things like the colour of the underbelly ans skin colour and texture but over the last few years i've found the easiest way to tell them apart is from 3 simplified indicators.
1. if you look at the lateral line on a flounder from the middle of the fish going back towards the head you'll see as you get closer to the head there is a clump of rougher scales either side of the line. on a plaice there are only a few in a single line rather than an increasing clump or none at all.
2. the orange spots on a plaice can almost be red at times or are more like a circle with a skin coloured dot in the middle. but in both cases the spots are striking and very strong instead of fainty marked.
3. on a flounder if you look from the back if it's eye to the lateral line you'll see it looks like a raised ridge of bone below the skin. where as on a plaice it is a row of boney nodules with a wee gap between each bump. it's usually a row of 4 bumps, but i have seen cases where there can be as many as 6.
but sadly the last nail in the coffin of your spotty orange flounder is the fact he is a lefty. plaice are exclusevly a right handed fish with less than 0.5% of the entire hatch ever being found to be left handed. to catch a left handed plaice would be very rare catch indeed. where as almost a quarter of the hatch of flounder revert to being left handed rather than right handed. the only species of flatfish where this occurs. so that in it's self makes your spotty fella still a worthy catch as you'll only see a few each year if your lucky

i hope this softens the blow as you thought it was a plaice. but a lefty flounder is still a nice unusual variation that some people never see
hope this helps for future identification man as they had us baffled for the first year or so too
i'll add a few pics to see if it shows better what i'm talking about. but never worry, with the ammount of fishing you boys get in, it's only a matter of time before you get your plaice
happy hunting
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