How long have you been able to just grab a mounted fish off the wall? I saw a few on Luna vendors and it struck me as strange so I walked up to mine that I've had on the wall for ages and I was able to pick it up and carry it around just like any other item. So, as a word of warning, lock down any trophies or they may "walk away". It applies to the new ones as well (luckily figured this out before losing my nice shiny 132 stone red herring!)