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Emerald Mithrax Crabs

Last Updated: 7/30/09

Grabby among some fake coral on 7/4/08.

My Emerald Mithrax Crabs
Crab Photos

I wish I had time to write about the various species and types of saltwater crabs. Instead, I will just tell you about mine.

My Emerald Mithrax Crabs

On 6/16/08, I went to the coral store to get some corals and a few more snails. I had no intention of getting any crabs. I knew they would sometimes eat animals (corals, snails, hermit crabs, fish, etc.) and would be risky. When I told the guy I had a lot of algae with bubbles, he said that I just had to get an "emerald crab" because they love bubble algae. I tried to get him to understand that I do not have "bubble algae" the species but algae with gas bubbles trapped under it. No matter, he said the crab was completely reef safe and great to have. So, I stupidly got the ugly little bugger. At first, he did not seem to do much, mostly hiding and picking at stuff. Then, he decided that he just loved my star polyps. He would sit and pick at the pink "skin" on the corals. They would close up for a long time because he would just sit there picking. There was no algae on the coral. He was actually removing coral flesh. I did some internet research and found out that they eat corals about half the time based on reports from marine aquarists. So, I decided to get him out. I first tried a net, two in fact. That was useless. So, I used tweezers and pulled him off the polyps. I hurt him a little bit which upset me but I was angry if I am honest. I put Grabby (my mother named him) in a plastic guppy breeding box within the tank. That messed with the water flow, giving some corals too much flow and others none. Plus, I had to tape the lid shut (the snails like to leave the water sometimes plus evaporation was an issue) due to the hooks on the breeding trap. The big box really had to go. What to do? The store guy's response was that I was wrong; he was 100% safe, put him back or take three hours to drive back and return him. I chose another route. I brought out my old 3 gallon Eclipse tank and on 6/21/08, I set it up. I put in a gallon of new saltwater and two gallons from the main "big" tank. I put Grabby in with some assorted shells, rocks, etc. from the main tank. He seems fine so far (just did it today). To read more about the tank, go to this page.

As of 7/26/08, Grabby is doing fine. He was eating a sinking shrimp pellet. I think the two margarita snails I added have died. I added another crab, a very tiny unknown crab that hitchhiked in to the 12 gallon tank. You can read about him here.

On 8/6/08, I moved Grabby and Scary from the 3 gallon Eclipse tank to a new 6 gallon Nano Cube tank.

For most of September, I did not see Grabby even scanning with a flashlight (day and night). The lights were out on the new tank since they died, and I had to wait three weeks for new ones! Finally, on 9/19/08, I saw Grabby hiding at the back side of the main live rock piece. He came up on top to feed the night of 9/20/08.

During November, Grabby was noticeable most of the time that I looked in the tank. I was certainly adding a lot of food but he did not seem to be growing. The evening of 12/11/08, Grabby was clinging to the live rock as he often did. He was waving his pincers at Dot, my female sexy shrimp, who was nearby. I was thinking, "I hope he doesn't bother her." The next morning, Grabby was near the same location but upside down. He was dead! There was no sign of injury or physical reason for him to have died. The other crab, Scary, is almost as big as him and did change hiding places after Grabby died. I doubt there was a fight because Grabby looked completely normal except he was dead. I took a few photos and was slow to dispose of him. He was about an inch long. I will miss him more than I thought.

The 12 gallon tank has developed more and more bubble algae and also short hairy algae. It got to the point where I was willing to risk putting another crab in the tank. On 2/1/09, I got Grabby Too and put him in the 12 gallon tank. I hope he starts popping some bubble algae. I know he will not get rid of it all but a reduction would be nice. The green star polyps are in good shape and will be okay if Grabby Too chews on a few.

I was surprised to find Grabby Too laying on the bottom of the 12 gallon tank on 7/30/09. At first, I was hoping it was just a shed exoskeleton but it appears to be his entire self. Something ate off a few of his legs but he was otherwise intact. I do not plan to get another mithrax crab. Grabby Too was well behaved but I do not think he ever ate a single bubble algae.

Crab Photos

Emerald mithrax crab on 6/16/08.

Grabby was in a guppy breeding trap for a few days. These photos are from 6/21/08:
Entire tank including the trap.
Grabby in jail. "Let me out of here!"

Here is a photo from 7/4/08 of Grabby sitting in the fake coral.

This photo from 7/26/08 shows Grabby at home in his 3 gallon tank on his live rock:

Here is Grabby on 8/9/08 enjoying his new 6 gallon tank. He is right in the middle of the photo.

Grabby on 10/10/08 at the top of the live rock.
Grabby - close-up from the last photo.

Grabby died suddenly on 12/12/08. I took these two photos.
Dead Grabby
Dead Grabby

Grabby Too on 2/1/09, in drip acclimation the day I got him.

Grabby Too on 7/18/09, a good photo for once!

Here is a link to the emerald mithrax crab on Live Aquaria:

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