Ignoring the temp differences of they supposedly acquire as I've known plecos to live in waters as cold as 30 degrees Farenheit. And I have a 55 gallon freshwater tank with a pleco inside of it. Yes. Just a pleco. Not one of those giant ones either. Like those ones you see at walmart. I really want to put my axie with it because right now he's in a 30 gallon tubaware bin, and he loves to swim around, so I want to give him as much room as possible. He's only like 5 inches now. My pleco literally does nothing. He stays in one corner of the tank just sucking on the driftwood.
Also, I don't know what kind of pleco it is. I got it from some shady pet store. It's light brownish with light dots around it. Basically it's like those blacks ones, but with a light brown tint.