Electroreception of catfish Ictalurus nebulosus in uniform and non-uniform DC fields: detection threshold and body length

Catfish are able to detect electric fields with their electroreceptor organs. It goes without saying that the electrodetection threshold depends on the sensitivity of the electroreceptor organs. The sensitivity in turn depends on a variety of extrinsic factors such as water temperature, conductivity, and electric field frequency. The aim of this study was to determine the effect of an intrinsic characteristic, namely body length, on the electrodetection threshold. In a two-alternatives forced-choice experiment, catfish of different sizes were tested in uniform or non-uniform direct-current fields. The results show no significant relation between body length and electrodetection threshold. The electrodetection thresholds are lower in uniform fields than in nonuniform fields. From this it is concluded that other factors than body size alone determine the electrodetection threshold.