The Star has tested (by DNA bank comparison) 12 sushi restaurants in Toronto, to see whether they are accurate in menu description and presentation of Japanese Sea Bream, Red Snapper, or Tilapia. Here is a link to the article: http://www.thestar.com/living/article...
I understand red Sea Bream is farmed in Japan, for sushi, and possibly to better standards than farmed and frozen tilapia, which can come from 'anywhere'. .
Genuine Red Snapper is usually wild, but there is some farming of Snapper, and I believe I have seen them in tanks at T&T.
The gist of the article is"You get what you pay for", and "caveat emptor".