Most of the great number of gymnotiform fish species from the Amazon near Manaus, Brazil, collected in 1978, could only be determined to the family level following their contemporaneous taxonomy (Kramer et al. 1981). That was also true for the Sternopygidae and Apteronotidae whose electric organ discharges were studied here (Kramer 2019). The whole collection of fish is now housed in the Bavarian State Collection of Zoology (ZSM), Munich, Germany where their taxonomic identity is being studied.