It is a firemouths. This used to be a planted tank with cichlids and my firemouths were breeding all of the time. My 125 gal started to leak so I had to do a quick shuffle. I'm fixing the 125 but in the meantime, my 55 is a brackish tank with a rogue firemouth that I missed during the shuffle. The crab is a blue Malawi crab. The shell is 3+ inches. Thanks for the feedback. I'll post a tank pic tomorrow.