Nancy Young wrote:

I see people talk about muddy tasting catfish and tilapia.
Today I got my Cook's Illustrated and they discussed this.
Long story short, they recommend an acid soak first, and their
acidic soak of choice is buttermilk. Soak for an hour before
cooking ... rinse off the buttermilk, pat dry and proceed with
the recipe.

FWIW.

nancy

In the one Indian cookbook I have (written and published in India) lime
juice is the recommended acid for treating seasonally-muddy fish.