Artemis Pharmaceuticals have just announced a second saturation mutagenesis screen of the zebrafish, Danio rerio. In this interview with Stefan Schulte-Merker, who is Head of Fish Genetics at Artemis, we find out more about the purpose of the second screen and contrast it with the first screen which was carried out in Christaine Nüsslein-Volhard laboratory and which is now called ‘Tübingen One’.Stefan Schulte-Merker has been working with zebrafish for over ten years and was involved in a number of genetic screens. He was also part of a team that produced a first-generation map of the ‘Goodfellow panel’ of radiation hybrids, which was intended to help in the cloning of the mutated genes. He is currently Head of Fish Genetics at Artemis Pharmaceuticals, in Tübingen, who are in the process of a second-round genetic screen, called ‘Tübingen 2000’.