Both Drosophila and zebrafish are used as animal models for studying human disease. Drosophila is advantageous for its fast development, easy maintenance, and suitability for genetic analysis. However, zebrafish are more suitable models for studies of heart disease due to their greater genetic similarity to humans as vertebrates and transparent embryos allowing heart observation. While both have high fecundity and are used for drug discovery, zebrafish have shorter generation times as vertebrates and are easier to work with.