My Fish are disappearing!!!

[nikki_kaiser]

My tank has been established for well over a year and a half now. I've had no water issues and everything has gone well except at one time I was having issues keeping shrimp but I believe it was because of where I was buying them and that has been resolved. My tank is 56 gallons and I had two percula clowns, one small yellow tang, one small coral beauty, a coral bandit shrimp and a peppermint shrimp.

I've since lost the coral beauty (just disappeared one day) and the smaller clown. I moved my live rock around and neither is anywhere to be found. There's nothing! How can they just disappear like that??? HELP!

 

[crister13]

They can die and get eaten by the cuc. The yellow tang may be being aggressive because he is in way too small of a tank, and is having territory issues now that he's growing. Him attacking them would stress the fish and then some sickness could kill them and then cuc lunch.