55 gallon only live sand for the first 3 weeks, live rock for about 1 1/2 weeks, added 2 yellow tail damsels, a shrimp, and 3 snails yesterday. One of the damsels began laying on its side this afternoon on the bottom of the tank, looks like its breathing rapidly, and occassionally swims in circles, slowly...and sometimes upside down. (Doesn't look good!) With my liquid saltwater test kit everything looks good ph is 8.0; nitrites, nitrates and ammonio are 0, and the salinity was within range. Do I need to go ahead and remove the Damsel? What else should I test?