Small vertebrate species, such as zebrafish (Danio rerio) and medaka (Oryzias melastigma/dancena), have due to their high homology to humans and the possibility to perform fast, high through-put and cost-efficient toxicity assays, proven to useful to safety assessing compounds for human use. The laboratory for Molecular Biodiscovery at KU Leuven has established a zebrafish and medaka platform where compounds like drug leads, cosmetics, water samples and foods can be exposed to larvae via immersion or injection. At various time points after exposure, developmental and organ specific toxicity (brain, liver, kidney, heart) and endocrine disrupting ability of the compounds can be assessed in a quantitative and functional way. In addition, we have developed an in vitro pre-metabolising method using rat or human microsomes which can be used to generate phase I metabolites of drugs ahead of toxicity assessment. Our toxicity assessment platform is available to industry and academia via contract research and collaborations.