The lake trout of the South if you will. There’s actually a fairly wide range in what catfish tastes like. Most catfish is farmed, and for whatever reason the stuff available around here tends to have a lot of moisture and is flaky and very delicate, to the point of falling apart while eating it. Catfish I’ve had further south is much meatier and denser. Farmed has a neutral flavor, while wild can taste muddy (I’ve never seen wild catfish for sale here though).
Closely related to whiting and hake but larger, cod is probably my favorite fish for frying—big, tender flakes that cleave cleanly, a good balance of tenderness and structure, neutral to sweetish flavor, and moist even after long cooking times. Cod is one of the fish most often used in English-style fish and chips, along with haddock. The term “scrod” refers to a juvenile cod (which, although obviously smaller, has sweeter, more delicate meat) but is sometimes misleadingly applied to smaller members of the cod family, like whiting or ling.
Thin, flat fillets that are very delicate, quite moist, and very neutral in flavor. Good if you like your batter-to-fish ratio very high.
Lake trout/whiting/silver hake
Whiting fillets are around a foot long and somewhat narrow, and you most often get two to a sandwich order. The flesh of lake trout from a place that doesn’t also sell fresh fish has medium flake, and is firm, slightly fishy, and slightly salty, as it has probably been pre-salted. Fresh whiting is almost an entirely different fish—significantly more delicate, slightly grainy, and pretty neutral in flavor. Some vendors will sell the less meaty and bonier tail sections separately, at a lower price.
Shorter, wider, and significantly smaller than whiting, this fish is slightly oilier, has slight grain, but overall is similar in flavor and texture to whiting.
Oyster trout/ling/red hake
The same shape but smaller overall than whiting, the flavor and texture are nearly identical. A sandwich order will usually get you three fillets due to the smaller size.
Steakfish is distinguished primarily by the pieces being cut perpendicular to the spine, whereas fillets are cut along it. This cut affects the texture—it is meaty, slightly fibrous, and fairly dense, while flavor is pretty neutral. It’s mostly boneless, but beware of small bones near the spine and around the bottom edges.
Widely available, almost always farmed, tilapia is flaked but quite dense, very lean, and moderately moist, and has that vaguely muddy, soil-y flavor that some freshwater tend to have.
Freshwater and—surprise—not actually a perch, it’s almost chicken-y in texture, pleasantly dense and not flaky, clean slightly savory flavor,