Calories in Mahi Mahi. The favorite choice for the term Mahi Mahi is 1 fillet of Mahi Mahi which has about 100 calories. Calorie and nutritional information for a variety of types and serving sizes of Mahi Mahi is shown below. View other nutritional values (such as Carbs or Fats) using the filter below: Calories|Total Carbs|Total Fats|Protein|Sodium|Cholesterol|Vitamins.