Crabs?

[Guest]

I was at the LFS and noticed they had fiddler crabs, those small little things, for sale in a community tank. The guy told me they do just fine in a community tank and are pretty much scavengers.

I have a few fish books that list all kinds of fish to put in tanks, but nothing on crabs. Opinions?

 

[robertmarda]

I like fiddler crabs and have kept some from time to time in my tanks.

Here are a few things to consider before getting them:

First, they are excellent escape artists. If there is an opening anywhere at the top of the tank they will find it and exploit it. If you are lucky you will find it walking across the floor before it gets lost or worse. So if you get any, make sure you cover all openings.

Crabs love to climb on things so be sure you have rocks and plants (fake) for them to climb on. If you have a high tank you can reduce the chance of them climbing out by not having anything inside the tank that goes from near the bottom to the top. I believe my crabs contributed to the demise of my live plants so you will need to watch that if you have any live plants.

Crabs molt and don't always survive the molt. If you can catch them molting that is cool to watch. It takes them a few hours to complete the process and the empty shell looks just like them. The first time this happened to me I thought my crab had died and threw it out. A day or so later I saw the crab in the tank and it took me a while to figure out what had happened. My point here is don't spend too much money for crabs. The most I have ever spent for a fiddler crab is $5 each.

It is helpful to the crab if you provide some flat cave areas where it can go to molt. Depending on the type of fish you have they may bother the crab a bit while molting.

Once I have a community tank again I will get crabs again as they are fun to watch.

 

[Voodoo Chilli]

Crabs, lobsters, and crayfish really are better off in a system set up for their needs and not in a community fish tank. Any fish small enough to look like a meal probably will end up being one and fish larger than the crab will often try to eat it while they're molting (and very vulnerable). Even if they don't actually get eaten, they can take lethal damage from those attacks.

You'd be much better off setting up a system for the fiddler crabs themselves: they'll be happier and you'll enjoy them more.

 

[Lance M.]

Wow robertmarda! $5 a fiddler crab! Down here you can just grab as many as you want from the beach.... Fiddler Crabs also need to be able to climb out into the air, they will die after a while if they aren't able to do this. All the info they provided is correct. And fiddler crabs are brackish.

You could always look into shrimp. They are very cool too.

 

[robertmarda]

I have also found some for $2.50. Unfortunately, they are don't seem to be as abundant up here near where I live in Virginia.

As I understood it fiddler crabs can do fine in freshwater. I think I had one for 6 months or longer. Most of mine died during molting. Anyone know of a way to help them survive a molt?

I didn't know they must have air. How long can they live without air?

A good place to search for crabs if you can't find them in the tank is to look in the upper (dry areas) of your filter. I spent a long time looking for one and went to bed without finding it. In the morning it occurred to me to look in the filter and there he was nice and dry and feeling fine. I put him back in the tank.