HCA: Hermit Crab Association

Fairly new to the crabbies. We’ve had 4 since August of last year. We believe most went through a molt shortly after we got them, and during December had only really seen 2. Too early for another molt? We had seen evidence of a potential fight— one detached leg on the sand one morning . Today one of the two crabs that were MIA for December has come up. It’s a purple pincher that had always been markedly lighter in color than the other 3, but now appears much more vivid.
Guesses on if this is the same crab that went down in this shell and molted again and changed color vs canabalism and shell changing below the surface?


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It is not unusual for a crab to molt a couple of times in short order. Or to just come up and go back down for unknown reasons. Do you have a big enough tank and deep enough substrate?

curlysister wrote:It is not unusual for a crab to molt a couple of times in short order. Or to just come up and go back down for unknown reasons. Do you have a big enough tank and deep enough substrate?

30 gallon and 6 inches. We’ve been trying to patiently wait to see all up from molting to add some extra substrate and larger pools. Which is why I’m wondering if “Sandy” developed a lot more color on this molt, or if “Sharky” ate him underground and stole his shell.


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They do change color with molting. You should be ok with 4 in a 30 gallon. I had 5 in my 29 at one point, they were all small, one of them almost medium. 4 jumbo crabs, I would say no but small, medium, large crabs, I think would be ok. Being new crabs, they need time to recoup from whatever they went through before you got them. Hopefully the one didn’t run into the other, I think your good on space per crab so I don’t *think* but being in any size tank, you can’t really be 100% sure. Just keep feeding them well and keep an eye out for the others.
Edit: you can add an inch of substrate every 24 hours, just don’t push it down and lightly set it in, so you don’t smoosh anyone underneath.