I have this blue hippo tang - going on 4 months now. He/she's been heathly, fat and growing like a weed - still is. He did have a small injury from a coral/anemone burn - but it healed and was in a different spot. Anyway - Over the last couple of days he's developed this white growth thing on his tail. He is not flashing, and is still eating, and swimming happily in the tank. None of my my other fish (tangs included) have this issue. Just wondering what this is, and should I treat? I don't have the best picture - this dude is FAST and I have a hard time with the focus. Here's the best one so far....I'll try to get a better one once the lights to the aquarium are a little brighter. I've also included a video which you can see the growth on. Any ideas?