My stars are falling apart. Please help!

[cgr]

The other day I received a shipment from SWF that included two brittle stars. Within three days I noticed that one of my sand sifting stars was missing two arms. This morning it was dead. I concluded that the brittle stars had killed it; however, I just noticed that one of my brittle stars is dragging its body around with just stubs left where the arms were. What can it be? I do have a very large sally light foot crab but I never thought of it as aggressive. Is it possible that the stars' arms just fell off? or is it the crab?

 

[ocellaris_keeper]

Brittle stars don't eat sand sifters, nor do Sally Lightfoots - you have another predator in the tank - check for a mantis shrimp - or you have a carnivorous fish.
what type of fish do you have? Check a compatibility chart. You be feeding one of your fish.

 

[cgr]

120 Gal FOWLR
1 Yellow tang
1 Blue tang
1 Sailfin tang
3 chromis
1 cleaner wrass
1 tomato clown
1 sleeper gobie
Ammonia 0, Nitrites 0, Nitrates 0, PH 8.2, Salinity 1.023