What would be killing emerald crabs?

[Reef_puck]

Fairy wrasse
Red cardinal
Fox face
Tomini tang
Royal gamma
File fish

Have a decent size bubble algae outbreak that I have added a number of emerald crabs for over the past few months but they are all missing.

Thought it was a Melanarus wrasse but I removed that and still missing crabs.

Ala any other options for removing bubble algae. It’s all over and in lots of crevices. Without me taking the whole tank apart to scrub.

 

[Randy Holmes-Farley]

Mantis shrimp?

 

[Schlafrig]

How big are the crabs and how big is your tank? I've had some smaller ones go missing for months then just appear again.

 

[Reef_puck]

90g. I have had small ones and larger ones.

 

[Tripod1404]

90g. I have had small ones and larger ones.

Maybe larger ones are killing the smaller ones?

 

[Uncle99]

I vote Filefish!