Bring a pot of salted water to a boil. Cook spaghetti until al dente, according to package directions.
While the spaghetti cooks, heat a couple teaspoons of oil from the tin of fish in a skillet over medium heat. Add breadcrumbs and toast until golden brown, 2-3 minutes, stirring frequently. Set toasted breadcrumbs aside on a plate to cool.
A minute before the pasta is done, heat the remaining oil from the tin of fish in the same skillet over medium heat. Add garlic and let it sizzle for 30 seconds.
When spaghetti is done, reserve 1/2 cup (120mL) of the cooking water and drain. Add spaghetti to the pan with garlic oil. Add tinned fish, parsley, and a few tablespoons of pasta cooking water. Toss until sauce completely coats pasta, adding more cooking water if needed. Taste and season with salt if needed. Serve topped with breadcrumbs.
