Right the Hillstream Loach is also known as the Butterfly Pleco and is a coldwater fish as is it's cousin, the Weather Loach aka DoJo Loach... and I'm sure others.
Many other types of plecos and suckermouth catfish can do well in water temps down to the low 70's to mid-70's(F). A BN Pleco (bristlenose) is often used in goldfish tanks since they do not grow very big and are generally peaceful. Like all pleco's they are mostly nocturnal so you need to drop some algae wafers into the tank at night for them to eat and also feed them fresh veggies, driftwood, etc.. The do not survive on algae alone.