We present a dataset of vertebral counts, body shape measurements, and lateral radiographs for 4861 individuals representing 583 species of African cichlids. This comprehensive dataset captures the full range of axial phenotypic diversity across the group. Using phylogenetic comparative methods, we show that elongate, body plans supported by high vertebral counts, evolved in lacustrine cichlids as adaptations to pelagic, demersal, and piscivorous niches. In contrast, riverine species exhibit broader axial diversity, driven by higher rates of vertebral evolution. Axial morphospace occupancy correlates with the age of lake radiations, but divergence time alone does not explain the observed patterns. Our results suggest that axial diversity radiated outward from an ancestrally riverine morphology and underscore the utility of African cichlids as a model for studying vertebral evolution in teleosts. Please see the README.pdf file for full descriptions of each data file deposited here. Do not hesitate to contact me at callum.bucklow@biology.ox.ac.uk/c.v.bucklow@gmail.com for further information.