Lobsters are saltwater, crayfish are freshwater and depending on the species, some can be kept in a 20 gallon but you might want to search the freshwater inverts forums for a lot more information on them.
i phoned my not so lfs and they said they have red lobsters 8.99 each and there 6 inces and he said there fresh water so my sg currently is 1.002 will it swim around or will it stay at the bottem does it need deco's gravel good or sand better
It would probably want sand, but I'm not positive.
Make sure to do your own research too. LFS's are usually not to factual, and are often misinformed. Also make sure the tank you have is for the lobster only, as it would make a quick snack out of any fish.
Try finding some information on Google.
♂ I assume you're talking about freshwater lobsters (actually crayfish, but I guess that doesn't sound as cool so people call 'em lobsters). I think they'll get 5-6 inches long, and a 20 gal is big enough, but I hope you don't plan on keeping any small fish in there too. These "lobsters are quite agressive, especially at night, and they will wipe out your smaller fish. Beware of these guys.
Umm Crayfish are ment to be dinner!!! not a pet!!! they will eat anything they can get. Snails small fish, slow fish anything!! I DO NOT suggest u keep them.
hmm NO I MENT SALT WATER LOBSTERS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
god if i say i wanted lobsters what did u think i want i know what a crayfish is