Send your fish back to water one last time before cooking for moister, more flavorful flesh.
In the test kitchen, we brine meats like turkey, chicken, pork, and lamb to improve both flavor and texture. But brining fish can be beneficial, too. We set up a series of tests using different brine concentrations (3, 6, and 9 percent salt-to-water solutions by weight) and types of fish (tuna, salmon, swordfish, and halibut). We found that, for up to six 1-inch-thick steaks or fillets, the optimum concentration was a 6 percent brine (5 tablespoons of salt dissolved in 2 quarts of water) and the ideal time was 15 minutes. It worked no matter the species, improving the texture of the fish without overseasoning.
As it does with meat, brining fish serves two purposes: One, it helps season the flesh, which improves flavor, and two, by partially dissolving muscle fibers to form a water-retaining gel, it helps prevent the protein from drying out. And brining works a lot faster on fish because the structure of muscle in fish is different than that in meat: Instead of long, thin fibers (as long as 10 centimeters in meat), fish is constructed of very short (up to 10 times shorter) bundles of fibers.
In addition, we seared each species of fish to see if using a wet brine would inhibit browning. Luckily, it did not, so long as the fish was dried well with paper towels just before cooking. Finally, we’ve found that brining helps reduce the presence of albumin, a protein that can congeal into an unappealing white mass on the surface of the fish when heated.