The objectives of this project are: 1) to develop an optimized breeding strategy to improve growth rate and survival of tilapia grown in shrimp ponds under fluctuating and unpredictable salinity, and 2) to assess the economic contribution of genetically improved tilapia in shrimp-tilapia farming systems. The project will deliver new fundamental knowledge about genetics of growth and survival under fluctuating salinities in tilapia, leading to an optimal breeding strategy for such dynamic environments. Expected impact of the project is the development of a sustainable breeding program for tilapia that supports an aquaculture production system that is accessible, affordable and applicable for shrimp farmers with brackish water ponds in Indonesia and elsewhere.