This document is part of a series of 5 technical manuals produced by the Challenge Program Project CP34 “Improved fisheries productivity and management in tropical reservoirs”. This manual is based on the experience gained by the partners of the project “Improved Fisheries Productivity and Management in Tropical Reservoirs” (CP34) funded by the Challenge Program on Water and Food. As part of this project, the partners designed, developed and tested in the field three enclosures in Lake Nasser in Egypt. The objective of the manual is to document for practitioners the main technical lessons gained from these experiments.