Here is what you do. Do you want to know how your water conditions are? Without testing? Get Rummies. The redder the head, the better the water. You can use them to guage water quality, as they are pretty delicate, and need good conditions. That is one of my guages for water quality. The other is my red tail shark losing color as well. Another sign that something is amis. Also, if you want something that schools very, very well, then I have 2 suggestions. Rummies in smaller tanks no smaller than 30G (To give swimming space), and Roseline sharks in larger tanks (minimum 75G, again to give swimming space). Hope this helps. I love all my fish, especially my GBR's and Roselines. Wish I liked my Bolivians as much as the GBR's, but they are getting bigger than I expected, and have an attitude problem, lol.