dead damsel, white stuff around mouth
I had a bi color damsel died last night. had it for 4 days. noticed white stuff around mouth looked like dead skin could see teeth as if skin was eaten away. only thing I put in tank was coroline stimulator. I got a 55 gallon with sailfin tang, very colorful wrasse, chromie, yellow tail damsel and a clown. 80 lbs of live rock,80 live sand cuc. I know I brought it from the pet store sick because I noticed it upon arrival. acclamated w/ a drip line ina clean bucket just like the others. Ate fine I think, tank parametes are great 0a, 0n, ph 8.0,nitrate 10. Fish was acting ok in my op.
I just dont want my others to get sick here is a pic.
What is it and how do I treat the tank in case of poosble contanimation?