Horseshoe Crab Compatibility
Hello All:
<Howdy Brendan>
First off I love your website. There is a tremendous amount of information.
<And more all the time>
I hope my question is a simple one. I purchased a small horseshoe crab today from the local pet store. (Approximately 1.5 - 2" Diameter ).
<Mmm... this is likely the coldwater N. American, Atlantic species...>
Within my reef tank, I also have a small dragon wrasse. This was purchased about one week ago. Just like your website says on this specimen, he is about 1.5" long and multi colored when sold in the stores.
<Neat animals. Beautiful, with much interesting behavior... A bit "destructive" when larger... called "Rock Movers" in many places>
After monitoring the horseshoe crab, the dragon wrasse was very curious (by nature) and followed him around for a little while. The dragon wrasse has not made an attempt on the horseshoe crab, but I would like to see if these two are tank mates or not.
<They are not compatible period... temperature-wise>
Thank you for your time. I look forward to your response.
<I really encourage you to return the Horseshoe Crab... It will not live long or well in a tropical setting. Please read here re:
http://wetwebmedia.com/hshoecrabsart.htm
and the linked files above. Bob Fenner>

Will my horseshoe crab eat my other livestock? (RMF, feel free to argue!) 10/15/09
Hello! I have read much of the information on this site and am very impressed. However I don't see my answer, so here we go. I just brought home a horseshoe crab from a guy that I was buying some live rock off of.
<Hope you have a large coldwater marine aquarium to keep your Limulus in; they are not tropical animals and cannot be kept in tropical reef tanks.>
I got lots of live rock, a clown fish, 2 zebra fish and an enmity.
<An enmity? Do you mean that? An enmity is a hatred. Do you mean an anemone? One of those big things with tentacles that looks like a jellyfish stuck to a rock?>
Well I got the fish and crab for nothing so I took them. The fish are doing fine tonight but the crab is all over the place, probably because of the current.
<He's looking for a way out of this tank and into a coldwater system.>
I didn't have much in the tank because I have only had it running for 2 months or so and am kinda new to all this. So I decided to come to your website and see what information you had for me! Well I panicked when I seen that horseshoe crab eat shellfish!!!
<Up to a point. But they are primarily detritivores that feed on small organisms and decaying organic matter they sift from mud. In captivity, scientists maintain them by taking them from the holding tank, putting them
upside down in a feeding tank, sticking some shellfish between their legs, and amazingly enough, they eat the shellfish. Leave in the feeding tank for an hour so they can defecate, and then return to the holding tank. They do this 2-3 times a week. While it sounds a performance, it's actually the best way to maintain Limulus for any length of time outside of a very large public aquarium. In a really big tank with a deep sandy substrate, they are to a degree "scavengers" that get by on leftover food and such, but this isn't really viable in home aquaria. We're talking tanks measured in 1000s of gallons here, which isn't what most folks have at home.!>
I Only had a few friends in the tank before tonight. They are 2 baby brittle starfish (maybe 1in. diameter) a Emerald crab, 2 blue hermit crabs, and a skunk shrimp. So immediately pulled this horseshoe guy out of my tank and put him in my sump for the night (lots of rock there with very little current and light). He's a little more calm there but, I need to know if this new guy means trouble for my other little helpers in my tank. I am trying to start slow, and do things right.
<He's actually doomed.><<I do agree. RMF>>
100gal tank
100lbs of live rock
2in of sand
<This is a weak link in the chain: you'd need a very big, very mature deep sand bed to maintain Limulus "naturally".>
1 horseshoe crab
1 skunk shrimp
2 blue hermit crabs
1 Emerald crab
2 zebra fish
1 tomato clown fish
1 enmity
1 colony of mushrooms
Dose anything above NOT belong together in a tank
<Yes, the Horseshoe crab doesn't belong. It needs a large unheated tank maintained at around 10-20 degrees C with a deep sand bed it can burrow into. If you can see the crab, it isn't being kept properly: in the wild they stay under the sand much of the time. There are tropical species, such as Carcinoscorpius, but this species is sold as a brackish-water "Mangrove Horseshoe Crab" and so far as I know not in the US, since the American trade has access to the cheaper Limulus. Even in Europe, Carcinoscorpius isn't often seen, which is a shame because it's smaller, highly euryhaline, and consequently easier to keep. Anyway, Limulus is one of those animals *not* to buy on a whim. Hope this helps, Neale.><<Well done. RMF>>

Lyretail Wrasse Hello, <Hi Jessica> My name is Jessica and I have a question about housing certain things together. Is it possible to house a horseshoe crab in the same aquarium with a lunar wrasse? Thank you very much.  <I wouldn't. They are an aggressive fish and crustaceans is on the menu. James (Salty Dog)> 

Horseshoe Crab/Compatibility 1/9/07 Hi, <Hi Joey> I purchased a horseshoe crab a week ago and just today bought some Camel Shrimp...I went to work and came home and just found their heads. <Mmmm cannibals in the tank.> Could my Horseshoe Crab have eaten them or did they die first?? I bought live cured rock today could that have been a problem?? <Well Joey, what else is in the tank besides the Horseshoe Crab?  Horseshoe crabs are mainly sand sifting filter feeders, although there are some species that are more predatory.  Depending on what specie you have, the crab could have very well ate them.  Again, you may have a fish or other invertebrate that had lunch on you.  As for dying first, could very well have happened depending on your acclimation method.  The newly purchased live rock; could have gotten a Mantis Shrimp as a not so nice bonus.> Thanks <You're welcome.  James (Salty Dog)> Joey