This probably isn't a bug - unless you actually know the solution and it isn't working. It doesn't involve the golden child.

[spoiler]

Hint 1: It involves fishing.





Hint 2: But not in the sea.





Hint 3: Is the villager you use a good fisherman?




Solution:

Drag a master fisherman into the lagoon, and he will hunt a strange fish. You may need to do this several times. It requires Level 3 of Farming to complete.
[/spoiler]