Do you keep the generally larger sturisoma sp. ?? Mine are all over the tank but mostly spend their time foraging on the bottom. From my observations, whiptails that fall into the rineloricaria group (like mine) are usually very flat from head to tail. This might have something to do with that type of behavior. Sturisoma sp. seem to be aero-dynamic in a different way. taller body where the dorsal meets, pointy "snout", and head not so flat. More likely to be seen hanging by its mouth from objects in the tank.