Missing Yellow Tang, Blood Fire Shrimp, Scarlet Cleaner Shrimp

[Alien2100]

First place I check as well, beyond that I'm thinking removing the serpent star and maybe the emeralds like you mentioned. If your sump/fuge will accommodate them without any dangers to them, that might be a good place for the time being. Just make sure they can't get into an area with pumps, or temporarily put guards over the pumps, safest would be foam. Just expect reduced flow and keeping them clean is a pain. Of course another established tank would be ideal, as long as there is nothing in that tank they might eat.
Just to ask though, have you noticed the serpent star looking any larger in his body?

 

[rcoapstick]

Just to ask though, have you noticed the serpent star looking any larger in his body?

Hes a little bigger, but he isnt huge to begin with. he is probably 6-7inches from tip to tip with his body being a little bigger than a dollar coin

 

[Alien2100]

Might be the culprit, especially if he looks a little bigger. I used to feed my star "not a serpent though" krill to keep him out of trouble and away from my feather duster and shrimp. Before, I fed him on a normal basis he would wonder the tank at night and get in to all sorts of trouble. What I noticed is if I fed him shortly before the lights went out, or right after they were out, he would eat bury himself in the sand to digest his meal and rarely go walk about at night. He actually seemed to used to this and would come to the top of the tank looking for food, before he mainly scavenged the rocks. Kinda defeated the purpose of him as part of a clean up crew, but kept him happy and my reef safe for many years. Before, I had a few invertebrates go missing, never fish though.

 

[rcoapstick]

the serpent has been moved to the refugium, the emerald crabs are a little harder to catch.

 

[Alien2100]

Not sure the emeralds were the culprits as much as opportunist, but if you wanted to go ahead and remove them you could try the coke bottle trick. Take a plastic coke bottle cut off the top about a 1/4 to a 1/3 down, turn it around and insert it back into itself. Then place in a small piece of meaty food, like krill or fish and place the whole thing in the sand at night. Once anything goes in it can't get back out, basically a small crab trap. Although it will catch just about anything that goes in there. In the morning you can see what you caught.
Note: If the emeralds are bigger then the neck of the coke bottle they can't get in, so might not work for them.
I have a link with pics of how the coke bottle works, but it's to a coral site, so not sure how RS would feel about me posting it. But you if you google coke bottle trap you'll find a few.

 

[rcoapstick]

I got the large emerald out and also the serpent. Both are hanging out in the refugium along with some snails and a few hermits. Do i need to feed them? there is some algae and some cyano in the refugium. There is also some chaeto. Do i need to suppliment their food supply?

The remaining emerald is a small one and the strawberry crab is pretty small too. I dont think they are able to catch a fish.

I feel like im not gonna know if this change helped any because the most vulnerable fish and shrimp have already disappeared. The yellow tang was small(about 2")

 

[rcoapstick]

SEE YA LATER CRAB AND STAR!!! Someone picked them up today.

 

[DesertOrchid]

Sounds like it is time to add some fish!

 

[phantom2991]

They would have to be some really big crabs to capture and kill a tang and two shrimp. My guess is the serpent star. I watched my brittle star snag my perfectly healthy cleaner shrimp and drag him behind the rocks where I couldn't get to him.

i watched my brittle star catch and kill 3 fish on 3 separate occasions before i was finally able to catch him and relocate him to the LFS. RIP mis-bar clown, leopard puffer, and copperband butterfly fish.