Sound production during courtship, dyadic encounters and in distress situations was investigated in C. paleatus. Fish emitted broad-band stridulation sounds made up of several pulses. Each sound corresponds to the abduction of one pectoral spine. The sonic mechanism was developed in all individuals. Males, however, had relatively longer pectoral spines (standardized to body length) than juveniles or females. Several males, which are usually smaller than females, court with one gravid female at the same time. Courting males emitted trains of sounds averaging 1250 ms in duration. During spawning one male clasped the female's barbels with his pectoral spine and inseminated almost all eggs. DNA-fingerprinting revealed, however, that a few eggs were fertilized by nearby males. Males did not behave aggressively towards each other during courting or dyadic encounters. During dyadic encounters males emitted shorter duration trains of sounds (mean: 850 ms) than during courtship. Single stridulation sounds were emitted in distress situations, i.e. when fish were hand-held in air. Contrary to courtship and encounter sounds, distress calls were produced by both sexes and were also recorded from juveniles. The dominant frequency of the sounds was negatively correlated to body weight. Sound duration was positively correlated to relative size of pectoral spines. This description of acoustical behaviour in corydoradine catfish reveals striking differences from the second callichthyid subfamily (Callichthyinae), where vocalization was observed during territorial behaviour in males and aggressive behaviour in both sexes (Mayr 1987).