There isn't a whole lot of use for raw fish other than cooking it.
Also, there aren't any house pets available in Valheim. Sure, you can tame a wolf, but it's not going to feel right inside your living room.
I say, "Kill two birds with one stone." If possible, create the option to find and/or tame something like a Norwegian Forest Cat. First, the cat might be programmed not to leave the house, becoming a truly tamed housecat. Or, Possibly not to leave a certain area around its home fire. It should also act as a comfort item. You know, the purr reducing blood pressure and all that. Perfect for after fighting a shit ton of Draugr.
To feed the cat, you would have to use raw fish in the cauldron, and the action would be "make cat food." This would also give people more reason to use the fishing rod.
For fun, you could pick the color and/or coat pattern of your housecat. For added flavor, if you make it so that the cat can roam in your base but not go outside the base, it would randomly drop field mice, squirrels, rabbits, or the like as "Presents" for you.
And, have Haldor weirdly like dead "cat presents" and pay like 1 coin for them. Necessarily, the time period between "cat drop offs" would have to be long as this is just a game flavor thing and not an actual quest/main part of the game.
What do a) the Devs and b) you other players think?
Source: https://www.reddit.com/r/valheim/comments/y3853e/idea_for_the_game_designers_housecats_and_a_use/