I purchased a Mandarin Dragonet the other day. I had a few to choose from and was careful not to choose a mandarin that seemed lethargic, sick, or injured. This one was actively swimming around the tank and after purchase and acclimation he proceeded to do the same in my tank and still is. The tank has been fish less for many months -since early june of 2016 - after my last fish died of ick. I purchased "trigger pods" and seeded the tank with them the night after tank introduction just incase the population in my tank wasn't enough. But suddenly I spotted this pale spot near his tale that I don't remember seeing the other day. He isn't exhibiting any abnormal behavior and is actively feeding all day. It doesnt look like ick it is a larger pale portion of its skin. It may be nothing but, I would prefer the opinions of others just in case. I've attached a short video the best I could take at the moment.
