Abstract: Danio rerio, commonly known as zebrafish, is a very suitable scientific model organism for studies involving vertebrate developmental genetics, cell biology, toxicology, high efficiency screening of drug libraries and human diseases. The evolution of the zebrafish into a favorable vertebrate model is due to several important scientific reasons, such as having a high degree of gene and amino acid sequence and functional homology with mammals, a fully sequenced genome, easy and inexpensive production and maintenance conditions, large number of offspring and rapid and transparent embryonic development. However, the organism takes its main strength from effectively applied transgenic tools, live cell imaging and cell tracking methods, forward and reverse genetic approaches, and micromanipulation techniques. One of the most striking features of zebrafish is that it has a very high regeneration capacity after damage or loss in various tissues and organs, including the heart, pancreas, liver, muscle, skin, blood and pigment cells, fins, and the central nervous system (CNS). Therefore, zebrafish is an extremely valuable vertebrate model to study the molecular functions of the body’s repair mechanisms against tissue loss and organ damage. A comprehensive understanding of regeneration mechanisms in any system requires a detailed description of the source of all regenerated cell types after injury. A number of genetic fate-mapping studies on zebrafish have revealed the source of regenerated bone, heart, liver, CNS tissue cells and melanocytes. In addition to this extraordinary regeneration ability throughout the organism, zebrafish can develop cancer in response to mutagen exposure or through transgenesis, and the resulting cancers have characteristics similar to those seen in humans at histological, genetic and transcriptional levels. This makes zebrafish an ideal system to examine the growth and metastasis of tumor cells and tumor angiogenesis in many types of cancer and for anticancer drug screening. For example, zebrafish, with its translucent skin, provide a very convenient platform for observing the growth of tumors and testing shrinkage in response to small molecule treatments.