I think it would be an awesome idea to introduce an option to fish in the GH house. When you walk around you notice flying fish shooting out of the rushing water. Why arent we able to magically catch one of those? I suggest putting Life element fish in the big lake near the tower.
There would be:
Mud dekoi Lifecuda chest (With GH rewards) Flying Grizzlefish. (1000 exp on initial catch then 10 exp)
This way you give the GH house some extra flair making it worth even more to craft it!
That's not a bad idea, but people with other houses and full house limits would not be huge fans. How about a craftable or gold-purchasable fishing pond outdoor housing item, which you stock with fish you catch, which then breed and make more fish for you to fish in your home?