You don't know what other features changed

I think the problem with GM is you don't know what other things change in the fish. I once saw a video in which a doctor told the audience that the wheat we currently use is GM wheat from the sixties with a whole range of unexpected features (ah, found it:http://www.cbsnews.com/8301-505269_162-57505149/modern-wheat-a-perfect-chronic-poison-doctor-says/). So I'm wondering whether they did enough tests and whether you ever could do enough tests to know whether it's safe...