I've followed this thread with interest partly because this bugger needs to be caught and partly out of concern for my wife and daughter who spend time alone there when I'm in the UK.
I don't like vigilantism but considering all have circulated the photo of said fish man among my Turkish friends most of who have lived in Fethiye for generations. One thing I know is that if this man is local someone will know him mainly because they all know everyone. Up to now no-one knows him.
I noticed on one post that someone said he was pretty good at filleting said fish. It could be that this lad is back room staff, chef maybe at one of the eating places in Calis/surrounding area. Sounds like he returns every year then disappears end of season.
If any of my people know who he is I will pm one of the moderators on here.
Good luck and take care all, Derek & Jacqui
PS, I have not said why I want to know who he is.