Dear Blue Lobster:
What do you guys think of keeping shrimp and crabs together? I was very close to buying some "mini crabs" from petsmart today but when the lady was trying to catch one i saw a lot of them were dead and decided i should wait until they got in some healthy ones, or just go to another store. But anyways, should the two species of inverts be kept apart?
Dear Gentle Sir:
I personally recommend mixing crustacean species to ascertain your own results on cohabitation compatibility. Many species are compatible and may actually complement one another, while others disagree spectacularly and engage in magnificent battles to the death. Regardless of the outcome, however, the only way to find out is to try!
Crayfish are almost always aggressive to other species, and such creatures will trigger their defense behavior. That is, the cray will become enraged and try to tear its tankmate limb from limb. For instance, a fiddler crab (Uca sp.) stands little chance against a cray and will, within minutes, become a twitching stub devoid of legs at the bottom of the tank. Fiddlers are social animals and do not have the aggressive territoriality that the solitary crayfish does.
Shrimp species are much easier to mix with crays, especially ones that lack enlarged chelae (pincers). Ghost shrimp, also known as Glass shrimp, are sold cheaply in pet stores and forage for detritus. Crays will eat them if they're fast enough to catch one, though more often than not you will find the shrimp peacefully riding the cray, picking its shell clean of debris. In turn, the cray will eat the shrimp when they die.
Other species are even more potential fun for cohabiting, however. For instance, the Shield Shrimp is an excellent addition to any tank with more than its share of slow, weak, or sick specimens. Fairy shrimp, brine shrimp, and daphnia are examples of smaller crustaceans that can serve as zoopankton for larger creatures. They also exhibit wonderful aquatic acrobatics as they wend to and fro in the swirling currents of your watery biosphere.
Please share the results of your experimentation with us, preferably with hi-rez pics!