Abstract: The macronutrients Na, K, Ca and Mg have been determined in 25 samples of seven common edible marine fishes. The samples were collected from the fish harbor Karachi, Moosa colony and Korangi creak area. The representative samples were drying ashed in quartz crucible and the ash was treated with the suitable amounts of concentrated HCl and few drops of concentrated HNO3 solution was then used for the analysis of Na, K, Ca and Mg by flame photometry and atomic absorption spectrophotometry. The macronutrients were estimated in flesh muscles of these species to check the nutritional quality of fish and potential of these elements in guts and gonads in contaminated coastal area and deep-sea region on the basis of recommended dietary limits at international level. The highest potential of Na, K, Ca and Mg in edible fishes can be related with the size, weight and feeding habits of fishes.