I bought a sixline wrasse a little over a week ago and it was doing just fine ... very active and eating well. Day before, I noticed at night that it was looking a bit spotted but I couldn't really tell if it was ich or not. I figured I would wait a day to get a better look and see if they fell off, but the next day I came home to find the sixline dead covered with a light white substance. Could the sixline have had ich and died that quickly? Regardless of what it was, how can I make sure my tank is fine for future additions? The tank is mature (over a year old) and houses a chromis and banggai cardinal that are looking and acting completely normal. I did a PWC
after removing the sixline but parameters are all normal - 0s except for nitrates between 10-20ppm.