I have had 3 fish die and cannot figure out what is going on... My tank contains: feather duster worm 1 speghetti coral mushroom polyps 10 blue legged crabs 7 lg snails coral banded shrimp red star sand sifter star 20-25 lbs rock blue damsel metal haylide and actinic lighting fluval 305 protein skimmer 35 gallon tank fish that died: small yellow eyed tang and cardinal purchased same time- died about 2 wks after purchasing, one morning tang was laying on side for awhile, then would swim around tank very rapidly, then lay on side again- by next morning it was dead. (We thought maybe adding one of our rocks might have stressed him out and also gotten sand in his gils?) About 2 days later, woke up and cardinal was also dead, with no physical sign of disease. 4 weeks later we purchased a tomato clown from lfs and 2 days after that woke up and it was dead also no sign of disease, acted healthy until found dead. levels checked almost daily always correct also take water to be checked by lfs when changing water every 2 wks. acclimate fish for 45 min with lfs water and our tank water. noticed few days ago bristleworm (2-3 inches maybe? only part was out of rock) in the rock that was placed in tank right before first fish died... Could bristleworms be killing fish? blue damsel still alive and well after 3 months (husband thinks we have a ninja damsel that kills other fish at night...) Bad luck buying fish or am i missing something?