How many emeralds?

If i did my math right i think you can get about 65940 emerald crabs in a 29 gal bio cube, however i would only recommend 3.
Good luck Travis!

 

I wouldn't add more than one or two to a tank that size. They are voracious eaters.

 

I only have 1 in my 72 bow.

 

I have 2 in my 120. Got them at eh same time a couple of months back. They weren't much bigger than the size of a quarter, not the small one is only a little bigger, but the other one is HUGE. When he puts his claws out in a "defensive" position, they must span 5-6 INCHES from tip to tip. Pretty cool. (For a visual, hold one of your hands like you are grabbing a 48oz supersugar slurpie drink from your local gas station, now look at your thumb and index finger and how they are positioned. That is his arm/claw span.)

I should get another couple some time.

 

Yeah, I wouldn't add too many. The one i had in my 14g biocube had a bad habit of eating my zoas and other softies. On the plus side, he kept the GSP in check lol