An in-depth analysis of hearing sensitivity for the jewel cichlid, Hemichromis bimaculatus was made using neurophysiological techniques to measure sensitivity at various levels of the auditory system and psychophysical techniques to measure whole-system sensitivity. For physiological studies, fish were stimulated by sinusoids generated by a loudspeaker or by direct vibration of the fish's head. Microphonic potentials were recorded from the sacculus of the inner ear and evoked potentials were recorded at several depths from the forebrain, midbrain, cerebellum, and medulla. For psychophysical studies, shock avoidance techniques were used in training fish to respond to tones generated by a loudspeaker. While audiograms based on the various neurophysiological and behavioral measures differed in detail, they showed in general that the auditory system of the jewel cichlid responds to sounds between 70 and 600 Hz, with best sensitivity in the region of 100 to 300 Hz. Evidence exists that within the frequency region of best sensitivity, the auditory system responds to both sound pressure and particle motion. The methodological difficulties in obtaining independent measures of sensitivity to pressure and particle motion will be discussed. [Supported by grants from NSF and NIH to R.F. and A.P.]