“What is it ” ?

” it’s sort of very much like a tarpon but it isn’t a tarpon, it’s fins are a lot prettier “

and for those who need it technical, it’s a Scardinius erythropthalmus or Common Rudd.

“Morphologically, this species is very similar to the roach (Rutilus rutilus), with which it can be easily confused. It can be identified by the yellow eye colour. The eye of the roach has a big red spot above the pupil, that can be more or less conspicuous. The rudd has an upturned mouth allowing it to feed easily at the top of the water.”

i’ve had the pleasure of catching these beautiful fish in several countries and in very different climates and it’s the upturned mouth and eyes that seems to be the better method of differentiation.
a bonus to this ‘upturn’ for us fly fishers is it facilitates surface feeding and they’ll readily take dry flies.