I had a small 1.5 Pakistani loach. its lived with a 2 inch bn plec. I have observed a shocking behaviour- the bn plec floored the Pakistani. it covered its entire head with its suction mouth, possibly crushing the Pakistani. thankfully this didn't happen to my larger Pakistanis. So my warning to all loach keepers is to be careful when housing plecs and loaches, especially if the plec is bigger.