In this study a detailed analysis of acoustical parameters of sounds produced by male Trichopsis vittatus, T. schalleri and T. pumilus during agonistic behaviour is reported. The calls consist of croaks which are composed of double pulses generated by modified pectoral fins. Calls of the three species are different in main frequency, number of double pulses within a croak and double pulse period. Croaks are uttered in series only in T. vittatus. Sound pressure levels are highest in T. pumilus, the smallest species. Amplitude of individual pulses of a double pulse are similar in T. pumilus and T. schalleri. Main frequency is negatively correlated with body mass in all species, but there is no correlation between sound pressure level and body mass. Differences in the calls of the three species suggest that T. schalleri is a distinct species. Furthermore, results indicate spectral characteristics and sound intensity could be of biological importance in fish.