I have a tank with 2 clownfish, and a goby with snails and coral.... well i did. Im extremely upset right now as i dont know what happened at all. Yesterday i went to my local pet store and got a Dr Tims Aquatics waste away, 3 new frags of Pulsing Xenia, a mushroom frag, and a coral i unfortunately forgot the name of. I introduced everything as normal by acclimating them to the water and i waited 30 minutes before releasing them. I woke up this morning at 11, looked at the tank which is literally above my bed, everything was normal i saw both clowns swimming near the heater, the goby im assuming was under a rock like normal because he had built 2 homes for himself. I turn lights on at 12 and leave them on till 8, so as i go to turn the light on i notice both clowns at the bottom of the water, the female breathing which i now have in a bowl with saltwater not from the tank and shes still breather and even seems to be getting some life back to her. The male was dead and i looked for the goby to save it too and unfortunately it had also passed, i just noticed a snail or two has now passed too at the bottom of the tank. Im going to be doing testing now and attaching some pictures in just a few moments. The corals and anemones all have their normal colors and dont seem to be affected. Im heart broken i thought i was doing everything right, biweekly 50% water changes, i was taking care of my phosphate and nitrate problem with the waste away, i have an ammonia monitor constantly in the tank which is still below 0.02ppm. As im typing this im watching the female slowly get better, i can only think it was an issue with my water but i dont understand how that could happen as i dont trust myself to mix properly yet, so i buy 5 gallon jugs of water from my local owned pet store. I do have a refractometer and the gravity seems to be in range from my ability to tell. I did mess with the calibration screw i think but it does seem to be around the same gravity as the water i just put the female in and shes very obviously recovering at least slightly in front of my eyes, slightly swimming in the bowl and no longer laying down on her side.