An odd observation, the tetras tended to stay closer to the bottom, once they were removed the Keyholes have gotten decidedly braver. Following the cues of the praecox, they're all over the place now, inhabiting areas of the water column (mid to top) they never would've before. I just can't get over how much the Keyholes seem to like the praecox. I've kept Keyholes in the past & I just don't remember them actually schooling with any fish but another Keyhole, love it!