Lake Malawi (A) is the most species-rich freshwater lake on Earth, and is home to an estimated 1,000 species of cichlid fishes that have diverged within the past 5 million years, including dozens of species exhibiting bower building behavior during the breeding season. Different forms of bower-building behavior have repeatedly evolved, with many closely related species expressing divergent “pit” versus “castle” bower phenotypes. The phylogeny is based on York et al. 2015 (York et al, 2015) (B). Bower building behavior is reliably performed in aquarium tanks. Advances in computer vision, depth sensing, and neurogenetic approaches will facilitate rigorous investigation of bower building behavior in the laboratory (C).