Figure 2. Characteristics of zebrafish models.

(A) Zebrafish are transparent and develop rapidly. Zebrafish embryos start forming major organs at 24 hpf. The transparency of zebrafish embryos is sustained until 96 hpf. Phenotypic changes upon exposure to drug delivery systems can be easily observed. (B) High fecundity and short generation time. A fertile zebrafish lays approximately 200–300 embryos every 5–7 days. Due to the high fecundity and short generation time, preclinical studies with zebrafish embryos can use large sample sizes, are cost-effective and can be conducted in a relative short time. (C) Numerous transgenic and disease models. Various models with fluorescent protein expressing organs are commercially available. Disease and knockdown models can be tailored for specific applications. (D) Systematic and genetic similarity to humans. Zebrafish models are phenotypically and genotypically similar to humans and hence suitable for prestudies. They have 70% genetic homology to humans, not significantly lower than widely used mouse models.