My fish keep disappearing... some found dead. Who did it?

[Keri_johnson]

We have a 6 line wrasse (hes an butt) for a year.
lawnmower blenny for 3 years.
A starfish for 2 years
Cleaner shrimp 1.5 year
Blood shrimp 9 months
Peppermint shrimp 6 months
Emerald crab 2 months
Porcelain crab 2 months
Pom pom crab a year. (Seen him three times including when I put him in)
3 BTA (came from one)
3 blue hermit crabs. (Have lost maybe 20 in 3 years)
3 sand sifting snails.
Everything in our tank is scared to come out until dark. (When the wrasse butt goes to bed)

Within the year we have had disappearance. 3 days it was a clown fish and today its buddy we got with him 2 weeks I our tank. We have also had 2 fire fish and a bunch of crabs vanish. We lost a cleaner shrimp (sheldon the first) and a not so nice damsel.
We had a velvet outbreak and killed 2 tangs a diamond goby mandarin goby and 2 clown fish it was so sad. But the blenny and wrasse survived. Then we waited 6 months. Got 2 clowns. Then they vanished. I cant put anything in the tank until I find out why things are disappearing.

View attachment 20190206_234847.jpg

View attachment 20190206_234840.jpg

 

[EmdeReef]

Welcome to R2R and sorry for your troubles!

Any ammonia? Do you quarantine new additions to the tank? You said you had velvet in the tank, did you treat in QT?

Have you noticed any aggression?
6lines can be very nasty especially to new additions but in general would hunt down other fish relentlessly, I.e.arent shy killers that you wouldn’t be able to tell.

 

[reef lover]

Six line is bullying to death or the serpent star is getting them...