The “Practical Training Manual on Doing Aquaculture as a Business for Small and Medium-Scale farmers” is composed by two modules: Module 1 “The Technical Dimension of Doing Aquaculture as a Business” and Module 2 “The Economic Dimension of Doing Aquaculture as a Business”. The target users are small and medium-scale fish farmers. The purpose is to enhance their knowledge and capacities in understanding and applying the basic economic and financial principles and concepts of doing aquaculture as a business in their daily activities. Module 2 first introduces the sustainability concept and its principles for aquaculture development, the definition and characteristics of both commercial aquaculture and non-commercial aquaculture and concept of planning of aquaculture as a business. It also shows small and medium-scale fish farmers how to assess the economic and financial viability of their fish farms. In details, it introduces the concepts and technicalities of cost structure, sensitivity , financial and cash flow analyses.