I have an emerald crab in both my tanks and they are rarely seenbut do not cuse trouble IME. As for getting any crab, well there are certain ones you should avoid. Red crabs are a definite no, arrow and decorator crabs are with caution but id advise against them especially in a BC14. I had an arrow in my BC14 who waspeaceful but short lived, there lifespan is very short, a year i believe. Stay away from large hermits as they will get too big and could eat small fish and snails. Good choices for hermits are electric blues, red, zebra and blues just make sure to have plenty of extra shells and you will be fine, staghorns are also very cool, readup on them first though. My fav crab, possibly fav invert is a pom pom crab. You can definitely have two in your BC14 and they are awesome, I have them in mine. Very peaceful as well. Stay away from horseshoe and sally lightfoots as thy ge too big. porcelian cfrabs should be fine for you, as well as anemone crabs which do not require an anemone. Good luck with your choice! Hope this helped