Back when I was a wee lad, I remember watching my grand dad cleaning a trout.. He would cut the anus of the fish out before cutting the belly open and cleaning out the guts. I was always taught of just sliding the knife in there and cutting up the belly so I always thought that was odd.. Fast forward to a few weeks ago. I was cleaning trout with my buddy and I happen to tell him of how my grand dad did it and he also thought it odd.. now, a guy came to the cleaning table and I was watching how he was doing it and lo and behold, he cut out the anus, just like grand dad did. Is there a reason for this or is it just a way someone was taught?