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Crabs

25 9:55:00

Question
QUESTION: Hi Robyn

I know this is a stretch but I was wondering if you could tell me what you know about aquarium crabs. My science teachers bought a crab for their aquarium at the local pet store a couple weeks ago and he has been acting weird. He has burrowed into the bottom of our RiverTank and he has been in his little cave thingy for about 4 days now. I can't see him, but it's pretty obvious that he's in there. Are crabs nocturnal? Should I be worried about him and try to fish him out or is this a natural kind of thing?

ANSWER: I've never had an aquatic crab (just a hermit crab).  I do know that they will eat most fish foods, small fish, other small animals, etc.  Crabs like to hide.  Some may burrow.  Some aquatic crabs are semi-nocturnal but I think most are pretty diurnal (active during the day).  What other animals are in the setup?  What are you feeding him?  Do you know the name of the species?  I would leave him be if he seems ok.  Sorry that I don't know too much about crabs.

---------- FOLLOW-UP ----------

QUESTION: Alfred (my classmates and I named him) is in our RiverTank ecosystem tank. There's plenty of light and theres plants outside and inside the water. there are a few ledges and inlets if he should feel inclined to crawl out of the water and sit in the sun. There's a school of danio and two tiger barbs in the tank. at the pet store where we bought him, the lady told us he ate shrimp pellets. so thats what he eats. i feed him about a dozen pellets every other day.

The lady at the pet store said he was a Red Crab.... but i looked it up online and the problem is that red crabs are, well... red. and he is not. he's a tan color. about 3 inches all the way across.

I noticed today in the tank something that looked like a crab-shell skin on the bottom of the tank. I think maybe the reason he's been hiding is because he's molting????? It sounds kind of bizarre but i think maybe thats whats going on.

I know this is stretching your knowledge.... is there anyone else on here who you could point me in the direction of who knows about crabs like this one????


thanks so much Robyn!!!
Shelby

Answer
I don't know much about crabs as I mentioned.  Just because the species if called red crab doesn't mean he has to be red or all red.  The species name may be correct.  I wish I had time to check for you.

When crabs molt, they hide much more.  If you've found parts of the exoskeleton, then he molted.

I'm afraid I don't have a list of animal helpers if you will who know about other animals such as crabs.  It's just me alone. Sorry.  I hope everything goes well with the river tank and crab!