SDS-PAGE analyses of venom extracts from several catfish species. Left lanes represent venom extracts, right lanes represent extracts prepared from fin tissue. Arrows indicate positions of unique venom protein bands or proteins found in greater concentrations in venom extracts than in fin tissue extracts. (?) represents ambiguity between smearing and an additional, unique venom peptide band. Large quantities of a 110 kDa peptide are found in the venom extracts of nearly all species shown, with the exception of Pimelodus. The presence and variation of venom peptides in the size range of 10-20 kDa is also clearly visible. Samples from non-venomous Ameiurus melas are shown for comparison.