Gathering and recording of biological data vital to experiments in a genetic improvement program should be carried out with efficiency, precision and accuracy. This is important in order to avoid marking erroneous conclusion about the results. The GIFT team has so far standardized the methods of measuring some of the important phenotypic traits in tilapia. These traits are noted and measured during breeding and fry collection, stocking, rearing and harvesting activities. This manual lists the guideline required for sampling and recording of phenotypic traits.