Jan 01, 2020 · 1. The zebrafish model1.1. Zebrafish natural habitat and life cycle. Zebrafish (Danio rerio) is a small (3–4 cm) freshwater fish belonging to the Cyprinidae family and geographically distributed in South Asia, including India, Bangladesh, Nepal, and also in the rivers ending at the Arabian sea (Spence et al., 2006).The typical natural habitat of zebrafish is shallow and slow