“Marlin often contains unhealthy levels of mercury and other toxins that may be harmful to humans,” says Appel. Avoid all striped marlin and most blue marlin, with the one exception being blue marlin caught in Hawaii. Or just skip the marlin steaks: “Halibut or sturgeon are good alternatives,” says Georgette Schwartz, who’s Board Certified in Holistic Nutrition and practices at Integrative Acupuncture in Delray Beach, Florida.