In 2000, more than one billion wild-caught and captive-bred fish were bought and sold in over 100 countries. The industry supports economies throughout the world, but with inadvertent ramifications. What pet owners do not realize when they buy plecos is how large they can become; sometimes reaching 20 inches (50 centimeters) in length. When the plecos grows too big for their little glass home, owners sometimes reintroduce them into nearby freshwater sources where they can become abundant and change the way ecosystems look and how they work.