Fish cooks faster than meat, so the main mistake is treating it as if it can tolerate long heat. Whole fish has skin and bones for protection, while fillets do not and need more precise timing.
Whole fish
Whole fish is convenient for baking, grilling, or cooking in foil. Bones and skin help keep it juicy, so it forgives a small timing error better than a thin fillet.
Before cooking, remove gills and any blood along the backbone, then dry the fish. Salt, pepper, lemon, thyme, rosemary, dill, and olive oil usually work better than complicated marinades: they support the fish flavor instead of covering it.
Fillets
Fillets cook according to thickness. Thin pieces fry or steam in just a few minutes; thicker ones need a little longer, but still cook quickly.
The center is ready when the flesh turns opaque and flakes easily with a fork. If the fillet stays on a hot pan or tray after that point, it dries out fast, so it is better to remove it slightly early and let residual heat finish the job.
Salt and brine
Salt affects not only flavor but texture. Delicate fillets benefit from a short brine: 3-4 tablespoons salt in 500 ml cold water for 20-30 minutes. After brining, pat the fish dry; extra water prevents browning and dilutes sauces.
For whole fish, salting inside and outside 10-20 minutes before cooking is usually enough. For tartare, ceviche, and other raw preparations, add salt carefully and close to serving because acid and salt firm the flesh quickly.
Pan, oven, and steam
For pan-frying, the pan should be hot and the fish surface dry. Wet fillets steam and stick instead of searing. Fatty fish can cook with very little oil; lean fish needs a little oil or a sauce after cooking.
Whole fish often bakes well at 200-220 °C: the skin sets quickly while the center stays juicy. Steaming suits delicate fillets that dry easily in a pan; after steaming, lemon, sesame oil, herbs, or a butter sauce work especially well.
Sauces and serving
Good fish sauces add a clear accent: lemon butter, herb sauce, caper sauce, light cream emulsion, or berry acidity for fatty fish. A heavy thick sauce should not overpower delicate white fish.
Serve fish right after cooking. If it must wait, keep the sauce separate and cover the fish loosely so condensation does not make it wet.
