I'm another who agrees with whitewave about 3 days vegi, couple of days fish and maybe 2 with meat.
I'm also careful about fish. I read that farmed salmon eats its own weight in antibiotic before it lands on our tables. I only buy red free range (is that the right word) salmon, never that awful pink slimy looking stuff that's been farmed. I'm also very careful about farmed sea bass, for the same reason. the fish are crammed together, covered in sea lice and fed all manner of chemicals as a result.
I was chatting to our vet about this, he's from the Highlands and still fishes for salmon there. He talked about diminishing stock and the impact of escapees from the farms. He said he believes farmed salmon is probably one of the worst foods we could possibly eat (he evidently eats a lot of meat)