When investigating or quantifying the interaction of organisms with the hydrodynamic environment, it is often necessary or desired to use surrogates instead of the prototype organisms. In order not to derogate the results, it is important to design surrogates to represent the essential properties of the prototype organism correctly. To do so, several aspects of organism behaviour and morphology have to be considered, which are rarely mentioned in studies that present work carried out with surrogates. This flow chart shows individual steps that need to be considered when procuding surrogates. It is designed to aid in deciding how to produce surrogates.