What the Petco guy says...?

[okiemavis]

A bristlenose (different name for bushynose) should work fine in a 14 gallon, although, get an albino one, as they tend to be a bit smaller. He'll get on great with your betta (or more specifically, they'll completely ignore each other). They're also plecos, just a very small variety and are very good cleaners. And, of course, don't add more fish until your tank has finished cycling.