Looks like a made a $70.00 mistake. Ouch. I've been watching my parameters and they showed that my tank had cycled (picture). I purchased two Clown fish and a Bennie. They thrived. So, several days later I purchased another fish (forgot its name). I went through the procedure to acclimate it to my tank, netted it, and released it into my tank. It disappeared. I thought it was just a bit stressed and was hiding. After two days I started to really look for it. I found it tucked under a piece of live rock. It was dead. I think it likely died in less than a day. Other than being dead I could not see any obvious reason that it died. My tank is now showing that its in the "Diatoms" stage of the cycle. Is this likely what caused it to die? By the way, what kind of fish was it (I have a bad memory)?