Dear Blue Lobster:
I was recently given 3 small crabs that look very much like the larger ones that people eat but these are smaller than a quarter around including the legs. I have never seen anything like them and would like to know how to care for them. They are not hermit crabs. They stay in water like a fish and have no sea shells attached to them. They were purchesed from a pet store so im guessing someone knows about them.
Dear Gentle Sir:
These crustaceans that you have are female fiddler crabs (Uca spp.). I find it curious that the pet store sold these crabs without some sort of label, but the description you provide indicates this gentle decapod. Fiddler crabs can be fun, but here are some rules of thumb to keep in mind while you care for them.
Multiple females are okay, multiple males are a bad idea. Fiddler crabs live in large loose-knit groups called colonies that may number in the thousands. Within each colony are smaller groups called clutches that usually number no more than 12. The group consists of several females of various ages and one dominant male. Immature males may also be part of the group, but generally males will not tolerate other males of breeding age. This social structure holds true in your tank as well as a beach, so feel free to add females to a group but never more than one male. Just because the pet stores stock many males and females together does not mean you should. Ever notice how many males are missing legs? Wonder why no longer.
Much like crayfish, fiddler crabs can breathe air, but unlike crayfish, fiddler crabs must breathe air occasionally. Filling a tank to the top isn't the way to go, so make sure you have plenty of rocks and supports where the crabs can emerge from the water. Also make sure that each fiddler crab has at least two and a half gallons to themselves. Keep the tank temp stays around 76 degrees at all times, and use bright fluorescent lights that mimic natural sunlight. Aquarium conditions are important for the health and longevity of your fiddlers!
Fiddler crabs prefer live food over dried food. Fiddler crabs don't have the largest mouth parts, but a small earthworm or maggot will fit nicely down their gullets. If you can't feed the fiddlers live food all of the time, try frozen blood worms. The fiddler crabs will benefit from the fresh nutrients and be healthier for it. A steady diet of dried pellet food will result in sluggish, lethargic crabs, so these pellets should only be used to add variety to the diet and not as a staple food source. Also make sure some sort of soft water vegetation is available for them to munch on.
Music is important in the life of a fiddler crab. During feeding Chopin or Brahms are appropriate, as the peaceful soothing melodies aid digestion. During the night even slower works are favored as they forage quietly on the tank bottom for leftovers from earlier and groom themselves in the darkness. During mating season the males love to wave their oversized claw around to the works of Wagner and Mozart. The higher frequencies are not so important as the lower ones are, so placing the sub-woofer directly under the tank usually achieves the best results. Your fiddlers will thank you for the music with increased activity and vibrant colors. Don't neglect this aspect of your new pets!
Don't forget to read up on these wonderful creatures both online and at your local library! They can provide hours and hours of entertainment for the whole family as they share their private crustacean world with you through the glass of the aquarium tank!