Globalization of seafood markets raises concerns about nutritional insecurity, as low-income nations trade away nutrient-dense seafood to high-income nations. However, this narrative ignores the nutritional contributions of seafood that low-income nations import due to reciprocal trade. We utilize a novel dataset connecting country-level seafood trade flows to product-specific data on nutrient concentrations to investigate how seafood trade affects nutritional availability to residents of developing nations in terms of nutrient density per dollar. We find compelling evidence across three macronutrients and nine micronutrients that developing nations pay lower prices for nutrition in imported seafood than developed nations. We demonstrate that import prices reflect values of nutritional characteristics but also premiums for freshness, particular species, convenient product forms such as fillets, and trophic level. We show that a significant portion of the nutritional bargain for low-income nations reflects differences in the non-nutritional characteristics of seafood imports between developed and developing nations.