I also do salmon (or tuna) croquettes (fish cakes/fish patties) but I've never tried mashed potato. Here's a common recipe
www.tasteofhome.com/recipes/speedy-salmon-patties (bear in mind that this recipe is will need 2 of your tins, and "saltines" are an American salted cracker (biscuit)
The one on the tin varies by the addition of a tablespoon of mustard. I vary it farther to make it Gluten Free by substituting crumbled Corn Flakes (the cereal) instead of saltine crackers (biscuits) that the recipe calls for.
Another use now that Summer is coming is a salmon salad:
-One tin of the salmon drained and crumbled
-One hard boiled egg diced
-About a tablespoon (or less to taste) of chopped gherkin
-A tablespoon of finely chopped onion
-A tablespoon of chopped celery
-Enough mayonnaise to dress the all the above once mixed
Mix all ingredients well, chill, and serve with crackers (biscuits) or spread over sliced bread.
Still another type cold salad would be a classic salmon and pasta salad:
-About 6 ounces of cooked and cooled pasta (adjust to taste)
-Salmon (2 of your tins drained and crumbled)
-about 7 ounces of black olives
-1/4 cup each of chopped onions and chopped celery
Mix all the above then mix with either mayonnaise or a vinaigrette type dressing. Serve at room temp or chilled.