Costco's Fresh Wild Flounder Fillet is a premium seafood option sold by the pound, sourced from wild-caught flounder harvested from coastal waters. Flounder are flat, bottom-dwelling fish with a delicate, sweet, and mild flavor that makes them highly versatile in the kitchen. Species commonly sold as flounder include winter flounder, yellowtail flounder, and American plaice.

Each fillet is boneless and skinless, featuring tender white flesh that flakes easily when cooked. The mild flavor profile pairs well with simple preparations such as pan-searing with butter and lemon, baking with herbs, or breading and frying. The best season for flounder runs from September through May, when the flesh is at its firmest and most flavorful.

Flounder is an excellent low-fat protein source, providing approximately 12 grams of complete protein per 100-gram serving with only 2 grams of total fat. It is rich in vitamin B12, vitamin D, selenium, iodine, and omega-3 fatty acids (EPA and DHA), which support heart health and brain development. Flounder is classified as a "best choice" seafood by the FDA due to its very low mercury content, making it safe for pregnant and breastfeeding women and children to consume two to three servings per week.