I've had 3 orange laser cories for a few days. They are acting perfectly fine, no problems breathing, swimming, no clamped fins, but I noticed on like the second day I had them that they had tiny whitish spots on them that they hadn't had before. I have a super-fine sand substrate that gets all over everything, and they spend a lot of time digging around in it. So I'm wondering if it's possible they just have some grains of sand in their armor, or if it's probably ich. I don't see white spots on any of the other fish in the tank-- banded pencilfish and celestial pearl danios-- but I have lost two fish in the last two days (one of each) and the pencilfish looked bloated today (eep!). Should I treat the tank? And with what?