Although silurids occur across much of Europe and Asia, they are most diverse in southeast Asia, beyond which their diversity decreases in temperate east Asia, the Indian subcontinent, southwest Asia, and Europe. Silurids are apparently absent from much of central Asia. The family can be divided into two groups, a temperate Eurasian clade and a more diverse subtropical/tropical south and southeast Asian clade.
These catfish do not have a spine before their dorsal fin, do not have an adipose fin, and the pelvic fins are either small or absent. The anal fin base is usually very long. The largest species in this family is Silurus glanis, the Wels Catfish.