Transplantable tumors are an accepted gold standard in cancer studies in rodents. The progress of this model in zebrafish has long been constrained by the lack of true inbred lines in zebrafish. We have generated several lines of homozygous diploid clonal zebrafish lines, which allow serial transplantations of tumor cells from one fish to another without sublethal gamma-irradiation. The spectrum of transplantable tumors that were initially induced and maintained in inbred clonal zebrafish lines was limited to different types of spontaneous and diethylnitrosamine-induced hepatic tumors. However, this model can readily be extended to a broad range of extrahepatic tumors, transgenic tumors with defined mechanisms of induction and fluorescence-tagged tumor lines. These models will further facilitate in-depth analysis of invasive tumor growth, angiogenesis, metastasis and tumor-initiating cells by in vivo imaging and provide a cost-effective system for high-throughput (HTP) screening of anticancer therapeutics, including biological response modifiers. In addition, homozygous zebrafish lines are an indispensable tool for immunogenetics, mapping of quantitative trait loci and other genetic applications. The whole procedure, from generation of a gynogenetic female homozygous fish (a founder) to obtaining 3-4 consecutive passages of a syngeneic tumor, takes approximately 12-18 months. This time-frame largely depends on methods of tumor induction, tumor type and tumor growth rate.