Reading through a sushi thread on the Manhattan board , I found some info advising one to eat at certain establishments on Tuesdays and others that said not to go to particular places on Tuesdays. I had always assumed that fish would be freshest on Monday and Friday, so I'd try not to go to sushi places on Thursday and Sunday. Yet, a sushi lover told me not to eat sushi on Mondays. I'm sure the really high end places get fresh fish every day, but what about more modest ones? Are there really better days to indulge, and why? Also, I wonder if some of the advice given to eat or not eat on certain days might have to do with a favorite chef's presense/absence. Thanks for any explanations.