The technique of X‐ray cinematography was used to study pharyngeal movements inAbramis brama(L.). The theoretical and practical problems in X‐ray cinematography of feeding fish are discussed, as well as criteria for the selection of images suited for detailed measurements.Respiration and filter‐feeding onDaphnia pulex(lengthc. 1 mm) show different gill arch movement patterns in bream. Slits between gill‐arches are kept smaller during filter‐feeding. In addition, during filter‐feeding, this inter‐arch distance decreases considerably in a posterior direction. The hypothesis that particle retention occurs on the slits formed between adjacent gillarches and their gill‐rakers is not supported by the