Data and Code Repository Description This is the data repository for manuscript Tuning Collective Behaviour in Zebrafish with Genetic Modification gate-analysis-20220405.tar.gz: The raw data and compelete data processing pipeline for the 2D swimming shape analysis. (Figure 2 in the manuscript) plot-experiment-schematic.tar.xz: The code to plot the experimental setup. (Figure 3a and 3b in the manuscript) analysis-one-fish-comparison.tar.xz: The code and data for the single--fish 3D behavioural analysis (Figure 3c in the manuscript). many-fish-analysis.tar.gz: The trajectory data and compelete data processing pipeline for one 3D many fish analysis (Figure 3d in the manuscript). plot-lengthscales.tar.xz: The code and data to plot the lengthscales and simulation results (Figure 4 in the manuscript). plot-shape-pca-method.tar.xz: The code to generate the PCA methodology summary plot (Figure S2 in the manuscript).