Some species of carnivorous plecos may eat other live fish, but generally, plecos are not predators, preferring to feed on dead fish.
Most species of plecos are more focused on feeding on algae, biofilm, larvae, and other foods. There are carnivores plecos, where only a few species may hunt by ambush. Most carnivore plecos will prefer other foods than live fish, although it can occur, mainly with fry.
Full article: Do plecos eat fish?
