A process for preparing fish bone powder according to this invention generally comprising at least 4 steps: pre-heating, removing of impurity, drying and milling to derive a calcium-rich bone powder product that contains calcium in the range of 18-22g/100g of the final product. In addition, the bone powder particle size obtained is less than 100 microns and contains high levels of protein, fat, and essential minerals, such as sodium and phosphorus. The source of bone can be obtained from any fishes, preferably from tuna.