I've recently upgraded my cories from a 15 gallon to a 40 breeder. I've also added some new cories to beef up the groups, and some congo tetras (who were unhappy being moved from their other tank, but it was getting a little crowded.) All of the sudden, I'm noticing all of my cories (I've got green, reticulated, and pandas) are all shimmering green! Some of them are just in certain areas, others are all over. I've never seen them look like this before, and I know that the green cories should be green, but is this a normal attribute for all or many of them? I'm also having some issues since I added the new ones. One of the new reticulated died from popeye and two of the greens died mysteriously. Basically, I'm hoping that the green sheen is normal, and not some sort of fungus or parasite.