Well hubby call this fish "the cleaning guy". We have this guy for almost 2 years now and he hasn't changed a bit. I can't recall his original size. I am glad though because usually they don't last long in my aquarium.
In the Philippines, in the aquarium trade, it is called the janitor fish. The suckermouth catfish is named for its sucker-like mouth, which allows it to adhere to a surface, as well as to hold and rasp at food. These fish are sold when they are young and small but they can grow to be a maximum size of over a foot to around 50 cm or so.
Suckermouth catfish are of little or no value as a food fish, although they are at least occasionally consumed over their native range. However, they are of great value in the aquarium trade in the United States.