Pseudostegophilus is a genus of pencil catfishes native to rivers in tropical South America. The members of this genus are obligate parasites that feed on scales and mucus of other fish.
There are currently two recognized species in this genus:
P. haemomyzon originates from the Orinoco River basin in Venezuela while P. nemurus is found in the Amazon basin in Brazil and Peru.[1] P. haemomyzon grows to about 5.7 centimetres (2.2 in) SL. P. nemurus grows to about 15cm (06inches) TL. P. nemurus is said to become attached to the gills, anal region, and fins of dead, dying, or disabled fishes.