my 3 do it aswell when there nosing though the gravel for food (think thay ping the gravel up the glass. your get use to it.
edit. 1-2 times a week i feed algae wafers (for the plecs mainly) and carnivor pellets and thay dont seem to do it as much
edit. 1-2 times a week i feed algae wafers (for the plecs mainly) and carnivor pellets and thay dont seem to do it as much