On Tuesday, I added six yellowtail tetras (Alestopetersius caudalis) to my 60 gallon tank. The tank also contains six butterfly cichlids (a. thomasi) that have been in the tank for four weeks. I thought the tetras would occupy the upper third of the water column. However, they shoal in the lower third of the water column mingling with the cichlids. The tetras are wild caught. They are also feeding off the substrate and do not come up to the surface for flakes.