 "P. extremus" reaches up to in length and in weight.Similar to "Schizopygopsis", "P. extremus" has a horny sheath on the lower jaw and spoon-shaped teeth that it use to scrape off periphyton and algae from stones, but it will also eat benthic invertebrates.An important food fish, "P. extremus" has seriously declined and is now listed as vulnerable on China's Red List.