Pseudacanthicus serratus is a species of armored catfish native to French Guyana and Suriname where it is found in the coastal river drainages where local fishermen state that it can be found in deep, rocky areas of main riverbeds. This species grows to a length of 16 inches. The whole body is covered with pointy spikes, which can cause bleeding injuries when touched with bare hands. Like many other Pseudacanthicus species this pleco has rather large fins.

The overall body coloration of adult P. serratus is dark black. Youngsters show bright white spots, which dissappear the older the fish get. In rare occasions also adult specimens can show small white spots.

This species is territorial and defends a certain area around its main cave. Especially in between males and towards other big plecos aggressions can be seen.