Well thanks Weizen,
it worked a treat, that previously hard and chewy flesh (when fresh) was exactly as I get in the Sushi restaurant having pulled it from the freezer and slowly defrosted it.
I didn't have the ingredients to do Sushi properly this evening, so I just had a quick Sashimi fest from the 1 fillet and it was wonderful!
I had no wasabi, ginger or rice, but I found a bit of tabasco and lemon (and of course Soy Sauce) made a great alternative.
I did wash the flesh a lot to remove the "fishy" scent and what I would assume to be an accompanying flavour, but that was because it was frozen with other fillets so the fishy smell from the outside gets around - but easily removed.
While I am still a little nervous about it being from fresh water rather than the sea or "chuck" as you guys call it, the flesh was clean looked just prefect so I figured it was OK. Although from fresh water the fish was clean when I caught it so I can't see that any parasite would have had chance to get into the flesh. But if someone knows different please post,
but I'm sure it is fine and I'll be enjoying much more of this on a regular basis without paying restaurtant prices, although I'll still be going back for the Tuna from time to time!
what a great find,
cheers,
Paul.