Zebrafish (Danio rerio) has been an important model organism in a variety of biological disciplines. Presently it is well suited for studies in genetics, toxicology, behavioural neuroscience and developmental biology. Zebrafish embryos exhibit unique characteristics, including ease of maintenance and drug administration, short reproductive cycle, and embryo transparency that permits visual assessment of developing cells and organs. Because of these advantages, zebrafish bioassays are cheaper and faster than mouse assays, and are suitable for large-scale drug screening. In the present study, we investigate bioavailability of different drugs in adult zebrafish and compared our studies with fish fry. The effect of drug compounds on fish fry and in blood and liver of adult zebrafish were studied through thin layer chromatography (TLC). We hopeful that the use of these techniques or methods will make the zebrafish a prominent model in drug discovery and development research in the forthcoming years.