Tuna steaks are firm, meaty and don't fall apart when cooking. Other types of fish that maintain their structural integrity when grilling, baking and pan frying are halibut steaks, snapper, wild caught salmon and Alaskan pollock.
Halibut
Halibut is a good substitute for tuna steaks because the meat is firm and will retain its shape when grilling, baking and pan frying. The taste is mild and won’t compete with sauces or marinade recipes used for tuna.
Red Snapper
Red snapper steaks are firm which make them easy to substitute for tuna in grilling, broiling and baking. The flavor is mild and won't change the flavor of favorite tuna recipes. Red snapper is lower in fat than tuna.
Wild Alaskan Salmon
Wild caught Alaskan salmon has a natural bright red color. Steaks are firm and ideal for baking, pan searing and broiling, just like tuna steaks. The flavor is mild and won't interfere with seasonings used in tuna recipes.
Alaska Pollock
Alaska pollock is a member of the cod family. The taste is mild and the white meat is firm which makes it ideal for broiling, frying and steaming just like tuna steaks. Alaska pollock is higher in cholesterol than tuna, salmon and red snapper. Consult with a physician regarding cholesterol intake and mercury levels in fish.