there are no plecs suited to cold water tanks, some like cooler water to others but all are still tropical fish.
the fish that commonly get called "Butterfly plecs" are more likely to be loaches (hillstream loaches), and yes these are fine in cold water tanks but like lots of flow
Chaestoma species, more commonly known as bull dog plecs are suited to a cooler tank with lots of flow. Their required temperature is around 20 degrees celsius. Heres a list of other loricariids and catfish around that temperature
Actually, your conventional chaetostoma (milesi and the striped unidentified spp.--essentially your two most commonly imported spp.) are from the Magdalena basin, not the headwaters. Mid to high 70's are preferable.
I just got a l187b bulldog pleco you can see photos on him in my post my new pleco.
He is the best allways out. Cleans the tank looks cut and like cool water they are from Hugh mountain streams in south America they are really hardy too once adjusted. They do love water movment. I keep my tank at 75f he is fine. They do fine in water as cool as 68F but the low 70F are best. I love this fish and think they are over loooked far too much. They are very simular to the BN pleco but I think they are cuter.
I highly recomend these fish. In there native land people keep them in fountains as algea control. They also eat them.
There are few differant kinds of Chaetostoma sp. (1) but the common kind that I have only gets 3".