I'm not sure if this is patch related, but I built a house on a pond with the stilted foundation, and when I set a sim to fish, they'll fish from anywhere on the first floor, within the house. All walls are complete too, so there's no way they're fishing through a gap.
http://i785.photobucket.com/albums/yy139/ElyseMakenna/fishing1_zpsdc85b235.jpg
http://i785.photobucket.com/albums/yy139/ElyseMakenna/fishing2_zpsf6d8b176.jpg
http://i785.photobucket.com/albums/yy139/ElyseMakenna/fishing3_zpsa7bb4515.jpg
http://i785.photobucket.com/albums/yy139/ElyseMakenna/fishing4_zpsdb338e64.jpg
EDIT:
Yes, I was using mods, but after I removed all mods and CC it was still happening
I only have the patch at the moment, the game hasn't yet arrived in the mail. I can check again when it does if necessary.
Patch Version is 1.55.4.022001
The game was a new start, in Starlight Shores, but I tried again, with Moonlight Falls, a new game, and it also happened.
The sims in Starlight Shores were custom made in town in CAS, the family I used for the test in Moonlight Falls was premade with the game.
I play on Window 7 with the disk for all games I own, with some Sims 3 store content.