Plecos, also known as suckermouth catfishes, are large fish that come in a variety of sizes and colors. These fish can grow up to 24 inches and require a tank size of at least 75 gallons. While plecos may look peaceful, they have the potential to become aggressive due to their territorial nature. This means that if you keep more than one pleco in the same tank, it is likely that they will fight for territory which could lead to them eating other smaller fish in the tank. So while it is possible for a large pleco to eat other small fish such as guppies or tetras, this behavior should be avoided by making sure only one pleco is kept per tank. Additionally, providing plenty of hiding spots and decorations around your aquarium will help reduce territorial disputes between multiple plecos so that they don’t resort to cannibalism.