Need help solving a mystery

He may be. I am now actively trying to catch him. One of the still alive anthias has damage marks on him so I am no 99% sure the crab is to blame. I am disappointing in myself for adding a fish that gets eaten by something in the tank. Not my brightest hour for sure. :-[

 

Two months ago, believe it or not, I caught my hermit looking crab it had black legs and it had grabbed my green mandarin and to the point where the mandarin was just barley alive but still kicking to release itself from the crab. I got the mandarin released but it died the next day because of the stress. That was my first unbelievable experience that I witnessed. So anyhting is possible out there. I just wish that i had shot a video of the exact moment.

 

that looks like a gorilla crab to me, i would just get rid of it.

 

He (crab) is now in the sump.

I still have one dispar left so not sure what to do with him. My goal was the have a small school, but not sure now if I want to add more.

 

Well, if you research it a bit, you'll find that they aren't truly "schooling" fish.

Anthias behaviour is referred to as "shoaling" and must be kept with larger numbers of females to males to keep them from becoming too aggressive to their mates... Seven fish of any type is a lot to add to a tank, and unless you had five females to two males, your males were probably outnumbering the females, which will cause unneeded stress. That plus a predatory crab which may have taken advantage of your stressed out fish could have caused this problem... or rather the fish were just too stressed to begin with and the crab picked on the weak ones...

Your best bet would be to get 3-4 females and one male... or 5 females and two males going forward...

OR, try to get a cheaper fish to shoal, like chromis.

There is no such thing as a "schooling" fish for the size tanks that 99.9% of people in the hobby keep.