A detailed analysis of acoustical parameters of sounds produced by male T. vittatus, T. pumilus and T. schalleri during agonistic behaviour is reported. The calls are built up from croaks which are made up of double pulses generated by modified pectoral fins. Call frequency is negatively correlated with body mass within all three species, whereas there is no correlation between sound pressure levels and body mass. The sounds of the three species were found to be different in main frequency, croak length, number of double pulses and double-pulse interval. Croaks were uttered in series only in T. vittatus. Sound pressure levels were significantly higher in We smallest species T. pumilus. Differences in amplitude between single pulses are similar in T. pumilus and T. schalleri. Results indicate that temporal patterning of acoustical signals may also be important for species discrimination in gouramis as in sunfish and damselfish. Furthermore, differences in acoustical signals demonstrate that T. schalleri cannot be regarded as a subspecies of T. vittatus.
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