Yes they are emarlds and they were the last 3 or I would of gotten 6 of them! Someone please help, I have a nitrites and just done a water change 2 days again, tanks was cycled with used media and had everything perfect after 3 moths of running. 2 weeks later I added the few fish and now I have a nitrite spike and one of my cories unfortunately I dnt think is going to survive but all others are fine. Do I do another water change what do I do? Never had this problem in my time of have awauriums