What is the difference between lean and oily fish?

Lean fish such as cod, haddock and tilapia store fat in the liver and have mild white flesh. Oily fish such as salmon, mackerel and sardines store fat throughout the flesh, which makes them richer and more flavorful.

Is tuna an oily fish?

It depends on the species. Yellowfin and skipjack are lean but very firm and meaty. Bluefin tuna, especially the belly, is oily.

What fish can I substitute for cod?

Haddock, pollock and other mild, flaky white fish in the same area of the chart work in most cod recipes.

What fish is best for grilling?

Firm, meaty fish like swordfish, tuna, mahi-mahi and halibut, and oily fish like salmon, hold together on the grill. Delicate fish like sole and flounder fall apart; bake or saute them instead.

Fish Chart: Lean vs. Oily and Delicate vs. Firm Fish

Two things decide how a fish should be cooked: how much fat it has and how firm its flesh is. This chart places common fish on both scales. Fish that sit near each other cook the same way and can usually be swapped in a recipe, so if the store is out of halibut, look at its neighbors.

How to cook each type

Type	Examples	Best methods	Watch out for
Lean and delicate	Sole, flounder, tilapia	Bake with butter or sauce, saute, poach, steam	Falls apart on the grill
Lean and medium	Cod, haddock, pollock, snapper	Bake, broil, fry, poach, steam, saute	Dries out if overcooked
Lean and firm	Halibut, mahi-mahi, grouper, yellowfin tuna	Grill, sear, broil, bake, kabobs	Very lean: cook just to opaque, or sear tuna rare
Moderate fat	Rainbow trout, catfish, swordfish	Pan-fry, grill, broil, bake	Swordfish turns tough when overcooked
Oily	Salmon, mackerel, bluefish, sardines, herring, Chilean sea bass, bluefin tuna	Grill, broil, roast, smoke	Strong flavor; acid like lemon or vinegar balances it

Making substitutions

Swap within the same box of the chart whenever you can. A mild, flaky white fish like cod can be replaced by haddock or pollock with no other changes. Moving across the chart works too, but adjust the method: an oily fish like salmon can stand in for halibut on the grill, but it will taste richer, and a delicate fish like sole should not be grilled at all.

Thickness matters more than species for timing. Use the fish cooking times by thickness chart, and the 10-minute rule: about 10 minutes of cooking per inch at the thickest point. Fish is done at 145°F, when it turns opaque and flakes easily.

Frequently asked questions

What is the difference between lean and oily fish?: Lean fish such as cod, haddock and tilapia store fat in the liver and have mild white flesh. Oily fish such as salmon, mackerel and sardines store fat throughout the flesh, which makes them richer and more flavorful.
Is tuna an oily fish?: It depends on the species. Yellowfin and skipjack are lean but very firm and meaty. Bluefin tuna, especially the belly, is oily.
What fish can I substitute for cod?: Haddock, pollock and other mild, flaky white fish in the same area of the chart work in most cod recipes.
What fish is best for grilling?: Firm, meaty fish like swordfish, tuna, mahi-mahi and halibut, and oily fish like salmon, hold together on the grill. Delicate fish like sole and flounder fall apart; bake or saute them instead.

Seafood recipes

More charts: Cooking times by thickness | Steak doneness chart | Beef cuts chart | Fish chart | Safe temperatures