This contribution demonstrates an application of correspondence analysis to length-frequency data of catfish (Ictalurus melas, lctaluridae) sampled by electrofishing in the Garonne River, near Toulouse, France. The available samples ranged from February 1988 to November 1990 and covered a total length range from 8 to 30 cm. The method applied allowed the identification of two groups of catfish, with those between 15 cm having a dynamics different from those above 15 cm. This is discussed with regard to the movements, vulnerability to the sampling gear, and individual growth of 1. melas at the sampling site.