Though it is getting closer to winter now, I know a lot of pond keepers like to keep plecos with their goldfish during the summer months. It actually caused a bit of a problem for the local store once it started to get colder. They would get sold out in spring, but when fall came they would end up with about 50+ in their bathtub tank.
Remember that the tank your fish lives in is his or her's whole world. Ask yourself this question, and answer it honestly: would you choose to live there?