Hi crystalwizard, don't quote me on this, but I once heard a rumor in-game that they'll be adding some fish to some bought-for-gold houses. Again, it was just a rumor I heard from other players, but in the meantime don't forget you can always go to someone else's house in Castle Tours and fish from their bundle houses.
From what I've seen, it's the houses that come with bundle cards that are having the fish added. I've got a Sultan's Palace and the lake and all of the ponds around the main building have fish now. I know the Zafaria themed one with the gorilla gift-giver also had fish added.