I don't have a recipe, sorry, but when I make a fish stew (for backpacking), I start by making a pre-mix with dried ingredients:
dried onions and garlic
dried veggies (a variety, depends on what I have in stock)
dried mashed potatoes
Cayenne pepper (ground – I put some "heat" in everything I make – ignore it if that's not your thing)
Put all these in a plastic zip bag.
In camp, with freshly caught fish:
Fillet fish (ie, remove all the bones)
Heat water and stir in the dried stuff.
Once the pot is starting to boil again, add the fish, and cook until it starts to flake.
Serve and eat.
Sorry I'm not specific on amounts, but no one who has eaten it has complained yet!