I made the switch from veganism to paleo. The humane treatment of animals is important to me, so I've choose wild caught fish over farmed. However, I know that there are higher mercury levels in wild fish than in farmed.
I'm looking for direction as to safe amounts of fish to eat while maintaining a commitment to sustainability.
Chris Kresser has an article (and one of the first few podcast episodes, perhaps the one where he discusses n-3 vs n-6 for an hour and a half non stop!) in which he basically reaches the conclusion that eating fish is safer than not eating it.
To the particular mercury concern, his explanation is that it's only an issue if there is not also Selenium (which there is, in whole fish) to bind to the Mercury and make it safe.