One derogatory expression for overcooked, starch-heavy packaged food is Standard American Diet. The acronym is SAD. Unfortunately, this acronym maligns more than just the food -- it also maligns millions of Americans.
One of the problems with TV dinners, Chocolate Frosted Sugar Bombs, and even much of the fresh produce sold in American grocery stores is that the ingredients are bought based on the price-per-pound. (Fast food is bought based on price-per-calorie; the price-per-pound of meat and grain takes into account protein content.) Much of the nutritional value of food is in micro-nutrients whose roles are still poorly understood. Thus, crops have been bred (or genetically modified) to achieve high yields per acre, with minimal labor -- regardless of whether the nutritional value is diluted. Similarly, animals have been bred for quick growth, and to put on more meat per dollar of feed.
Farm-raised fish is fed a grain-and-soy based diet, just like most American meat animals. (Animals raised on grain-and-soy have different hormone balances and contain different fats, so their nutritional value is arguably "debased".)