I Think My Fiddlers Hooked Up

Dear Blue Lobster:

I recently found myself babysitting a fiddler crab. I set up a small tank for him with rocks to climb and shells to hide in. I bought another crab and the only one I could find in my small city was missing one claw. I’ve had them together now for about one month and the new crab seemed very dominate, hogging food and chasing the other away whenever he got close, so I assumed I had a male. Well, last night they both holed up in the same large shell, which was a shock for me. Today she is hiding out. Should I be concerned? I’m afraid I may have a pregnant crab showing up soon. If that is the case, what do I do with all of the eggs? I read she will have hundreds of thousands! I’m not prepared for that at all! I’ve put a lot of effort into saving the life of the male and after reading your website, I do think I need to do more for the crabs. I’ve grown quite attached to them.

Thank you!
Vicki

Dear Gentle Sir:

It appears as though your Fiddlers have "hooked up," the scientific term for mating. Do not confuse the term with current popular teen slang, however. Fiddlers actually do hook up using their specially adapted swimmerets, kept hidden within their curled tail, to grasp on to one another as the male forces his sperm load into the female.

There are a few ways to tell if your female is pregnant. One is to watch for odd behavior. If she begins eating unusual foodstuffs, such as aquarium plants, gravel, or her own feces, something has definitely changed physiologically within her. Depression and mood swings are another telltale sign. Is she staying in her cave longer than usual? Another way to detect pregnancy is to watch for mucus forming on her underside, which precipitates before her eggs flow down from her ovipositor.

So what do you do if your female is indeed pregnant? Comfort her. Her man has kicked her out and will no offer care for her children — in fact, he may try to eat them! Make sure she has plenty of nice landings she can climb out of the water onto and many deep caves she can disappear into.

Also supply her with round-the-clock food. Fiddler crabs are detrivores, meaning they'll eat just about anything as long as it's small. Makes trips to your local food co-op or farmer's market to procure organic veggie leftovers from their trucks and bins. Food from supermarkets are often sprayed with chemicals and wax, which are definite no-nos for a pregnant crustacean.

Once she's in berry (visibly carrying eggs) the eggs will hatch within two weeks. At this point it's time to decide how to isolate her and her brood from the other creatures in the tank, who will without doubt see the crab larva as tasty treats. You can relocate her, which threatens her and her brood with new water chemistry, move the other creatures out of the tank, which may be convenient depending on the number of tankmates, or install a partition which limits her space but makes life for the aquarium owner the easiest.

The children will need fed nothing special in particular since in their earliest stages they'll eat microscopic algae and detritus. As they settle down and begin molting, however, give them a small crumble of flake food daily. In some cases, where the crabs were isolated from food for too long, scraping your skin or shaking dandruffy hair into the tank will give them enough nourishment for the time being.

After the crabs begin to grow, only a small amount of the total will make it to adolescence. Use the Chimwich-Hayes equation to arrive at the ideal number of crustaceans for your aquarium and use the Internet to sell the others. Some species of Fiddler crab young can net as much as 69¢ per pound!

Good luck to you and your Fiddlers. Motherhood is a special blessing indeed.

Crayfish vs. Blue Lobster

Dear Blue Lobster:

I am a soon-to-be crustacean mother and I have an empty 100 gallon tank I won a few years ago I hope to add a Blue Lobster and Fiddler crab to, in addition to Ciclids and hopefully a Pleco. However, I'm quite confused by the whole Lobster vs. Crayfish information I've been getting online and in stores. Are ALL Blue Lobsters, Crayfish? And visa versa? Or is there a diffference? If so how do you tell? My tank is certainly large enough to sustain a 2 pound lobster (the size the store clerk told me the Lobster, NOT CRAYFISH mind you, would grow), and I don't want my children fighting or eating each other! I am also concerned my Lobster or Crab will eat or attack my bottom swimming Pleco, although I hope the size of the tank will allow for each to claim it's own territory. Thank you so much for all the wonderful info.

Concerned Mother To Be

Dear Gentle Sir:

Lobster and crayfish are the non-scientific names for different, though closely related, groups of decapod crustaceans. Crayfish refers to three families of freshwater species. Lobster, on the other hand, has traditionally represented the Homarus genus, which includes the saltwater American and European lobsters. The term is also used for other marine species of various types.

In the aquarium trade, exotic animals sell for higher prices than mundane native animals, and so to advertise their animal shops often blur an animal's name. To directly answer your question, all freshwater lobsters sold in pet stores are crayfish. Electric Blue Lobsters are almost always either blue color morphs of Procambarus clarkii or Orconectes alleni.

The connection gets muddier more recently, however, as dying the cray's water blue or subjecting the cray to special lighting which causes the cray to temporarily change color. In some cases dealers actually inject blue dye into the cray which shortens the cray's lifespan considerably.

True blue crays are rare in nature but are being bred more reliably as time goes on. In turn, the price of (true) blue crays should fall, but the aquarium industry is a notably lavicious one and prices may remain high. The fraud inherent in the cray trade makes for a tricky and sometimes dangerous foray into crustaphilia. Approach blue lobsters with skepticism and care.

How to Be a Good Molt-Sitter

Dear Blue Lobster:

Just two days ago I purchased a Watermelon Fiddler at a local pet store. Currently, it is lying on its back motionless. I have read your posts on molting, and I would like to know how long it typically takes for a fiddler crab to molt. How long I should wait before I consider it to be deceased? It has a strange arm-like structure rising from its underside. Thank you for your time, I appreciate your advice and love your site.

-Josh

Dear Gentle Sir:

I regret to inform you that your crab has died during a bad molt.

Death by ecdysis is a common way for crustaceans to bite it. One of the risks of ecdysis is that the process may leave the animal in a lethal, half-molted state as your crab was. The only way to ensure the molt goes as well as possible is sitting, or closely monitoring the molting process.

While sitting your crab, you'll need a notebook and pen, a camera (digital or otherwise), some sort of audio recording device, a flashlight, fresh bottled water, and an intimate knowledge of the molting process. You also can not molt yourself while sitting for your creature during its molt.

Your best bet if the crustacean appears distressed is to remain quietly watching it; molting is a slow process and reaching in with the surgical scissors too soon is just as harmful as doing so too late. This is the classic "do no harm" vs. "don't just sit there, do something!" dichotomy.

All difficulties aside, here are some general tips for molting:

• Turn the tank off or, if they're set to a dimmer, down. Your cray will need to relax during the molting process.

• Keep inquisitive or predatory creatures away during and after your cray's metamorphosis. They will smell the cray's condition and attack.

• Do not offer food, as the cray won't eat during the molt and any food in the tank will spoil.

• Keep your filtration system turned down as the suction can crush your soft cray faster than you would be able to rescue it.

• Play nature music. Underwater recordings mimic the birth process which is similar to your cray's molt.

Good luck and remember to watch our for that "third arm" that is the telltale sign of a molt gone bad.