well said, Catostomus are carps that remain still in the bottom a lot of time. They are not big swimmers. Their main concern is to suck a rock with enough force to stand their ground against currents. Remaining in waters with a lot of oxygen, that just travel straight to your gills, is like a holiday for the heart.
Are cattle doing cardio because they're standing while sleeping?
I see what you're saying, but fish don't have to do a lot to station keep.