There are literally hundreds of different types of plecos and depending on what kind you have, it may eat meat (Hypancistrus, Pseudacanthicus, etc.), or wood (Panaques), vegetable matter and algae (Ancistrus), or everything from meat to veggies (Pekoltia, Barycancistrus, common plecos, etc.). Even the more herbivorous species will want some protein once in a while.