Three bacterial proteases were selected for their activity on casein per unit cost. Conditions for inactivation were determined. Fish protein was hydrolyzed without water addition. Protein was solubilized faster with Pescalase 560 than with HT-200 or Protease N. Increase of protease concentration was associated with a quadratic increase in soluble nitrogen. Yields of 13 to 15% in terms of whole fish were obtained at the pilot plant. Products contained 83 to 86% protein of which 70 to 80% was soluble. Reactive lysine was 70 to 85%. Nutritional evaluation with rats indicated hydrolysates had 10 to 15% lower nutritional value than casein. Results suggest fish protein hydrolysates can be used in the food industry for their solubility and nutritional value.