Zebrafish is an attractive model organism for studying apoptosis development because of its genetic accessibility. Here we describe the induction of clonally derived apoptosis in transgenic zebrafish expressing mouse caspase-3 (CASP3) under control of the zebrafish beta-actin promoter (beta p). Visualization of apoptotic cells, expressing a chimeric transgene encoding CASP3 fused to green fluorescent protein (GFP) gene, revealed that apoptosis arose in the thymus, spread locally into gill arches and retro-orbital soft tissue, and then disseminated into abdominal organs like testis, kidney. This transgenic model provides a platform for over-expression of caspase-3 induced extensive apoptosis in embryos and adult.