Salmon fish head soup is quite low in calories and therefore is a good addition to your daily diet, especially if you are on a weight loss diet. Remember that fish itself is an excellent diet food. It gives you proteins and fatty acids and therefore is extremely nutritious. Fish is unhealthy only when extra calories are added on during the cooking process. For example, deep fried fish would not fit into any weight loss program. But fish soup is perfect - it's healthy, nutritious and filling. So yes, you can go ahead and indulge in salmon fish head soup while on a diet.