Catfish is a moderately fatty fish and an excellent source of protein. A three-ounce serving of catfish has: 120 calories 6 grams of fat 55 mg of cholesterol 16 grams of protein Eating catfish fillets will provide you with healthy fats, vitamin B12, and heart-healthy omega-3 fatty acids. Even though catfish is low in calories, frying catfish, while a popular cooking method, will add to the calorie count. Shop for catfish fillets on Instacart and make your day a little easier. You can have them delivered in as little as 2 hours!