I have also noticed that fish that you discover through conversation no longer appear in your household collection tab and I too don't know if the change was by design or unintentional. I'm inclined to believe it was intentional, perhaps it was never intended for them to add to your household collection and just the notebook.
It also impacts on the fish you can add to your pond since you can only add fish that are in your household collection, not those in your notebook per this screenshot.
I agree having fish learned from discussion go into the collections tab definitely made completing the Angling Ace aspiration very easy. It is still a lot easier than it used to be since originally the 20 fish had to be out of the original 22 base game fish, now any 20 fish in the game count (ie including the two added with an update and ones from packs), that change happened with the pre Island Living fishing update.
Best regards,
Jennifer
