Yep Tuna is fine. If it's tinned Tuna it needs to be tinned in brine or spring water - the stuff in oil would have syns.
As far as I know, any sort of Breaded or Battered fish is synned.
Am actually thinking of doing a fish week myself next week (my weigh in tonight so my SW week runs from a Thursday)
I think you just need to be careful about the tuna though, because I've read in quite a few places that you shouldn't eat Tuna any more than three times per week due to the Mercury content in it.
Hi, sorry to butt in but was also thinking of doing a fish week, does anyone know if Iceland's frozen fish - like plain tuna, salmon, haddock etc is free??