Large Emerald Crab Agressive?

ajones2n · Mar 27, 2015

I found my emerald crab I bought back in August dead a little less than two months ago. Tested everything and found no reason he should have died. So I went ahead and bought another. Well two days ago I found my new emerald crab dead. Tonight I came home to find a rather large (2.5-3.5") emerald crab that I don't recall having ever added to the tank. Could he have taken out my other emeralds? Does he pose any threat to my fish?

NanaReefer · Mar 27, 2015

Emerald Crabs are equal opportunity predators

Got a sump?

ajones2n · Mar 27, 2015

Dowtish · Mar 28, 2015

These crabs molt in order to grow. Either the first one you had never died and you threw away its molted shell. Or the new one you bought immediately molted when you added it to the tank, which has been reported as fairly normal when added to a new system. Once they molt, you usually dont see them for a while because their new shell is very soft which makes them vulnerable so they hide until it hardens up. I am willing to be your first one has survived all this time and killed the second one.

ajones2n · Mar 28, 2015

Huh. Never knew this that is probably what happened. What I threw away was very white so that would make sense. I just assumed it was because it died. Dowtish how do you find all this random information? been there done that got the t-shirt?

Dowtish · Mar 28, 2015

ajones2n said:
Huh. Never knew this that is probably what happened. What I threw away was very white so that would make sense. I just assumed it was because it died. Dowtish how do you find all this random information? been there done that got the t-shirt?

Im sure I read it on the forums somewhre along the way. Just like you did.

saltyphish · Mar 28, 2015

I agree. Your first crab is still alive. Imo get it out. The big ones seem to cause problems.

Dowtish said:
These crabs molt in order to grow. Either the first one you had never died and you threw away its molted shell. Or the new one you bought immediately molted when you added it to the tank, which has been reported as fairly normal when added to a new system. Once they molt, you usually dont see them for a while because their new shell is very soft which makes them vulnerable so they hide until it hardens up. I am willing to be your first one has survived all this time and killed the second one.

SnailQueen · Apr 3, 2015

Was looking for some other info on emeralds and found your post. Definitely get it out or confine it. I've had one for almost a year now that was fine until it got to be a little larger than a quarter, then he turned into a monster we now refer to as King Kong Crab. He took out a smaller emerald, a collection of tiny hermits, a yellow ball sponge, a chalice frag, and has made multiple attempts to murder a thorny oyster. He showed no interest in the food I was adding to the tank, preferred to eat random stuff instead. I can't bring myself kill him, so he's living out a life sentence in a whiskey glass I stuck in the bottom of my 10 gallon......