The paddlefish perceives its world through an array of electroreceptor organs spread over its rostrum. Using Detrended-Fluctuation Analysis (DFA) we find long-range anti-correlations in sequences of time intervals between neural action potentials recorded from spontaneously firing electroreceptor afferents. In contrast, spontaneous discharges from mechanoreceptor afferents in the crayfish tailfan lack long-range correlations altogether. We interpret this finding as a consequence of the self-sustained oscillatory nature of the electroreceptor organ compared with the threshold-type dynamics of the mechanoreceptor.