first of all try not to get rats from a pet store. many are sick, may have temperament issues,etc. AND you can get a tailless (manx) from a reputable breeder. rats come in may coat colors, fur types, and dumbo or standard ear types.
rats in my opinion make great pets. i prefer the males to the females because the males are more laid back. if you want a rat that would love setting in your lap and being petted, get a male. if you want a rambunctious exploring pet then get a female.
rats MUST be kept in at least pairs. they are very social and no matter how much attention you give them you are not a rat.
i would also suggest making your own food because 80% of the food out there for rats has too much protein, and stuff in it they wont even eat. i have a great recipe for something called suebees mix that i fed mine.
rats do require quit a bit of cage space. i build my two a large 3 story cage out of a low raise plastic storage bin (for the base) and welded wire mesh for just 12 dollars.
Martins cages is a brand that lots of rat people recommend if you can afford them.
no pine or cedar bedding. if you want a wood bedding use woody pet, or aspen. i have always preferred shredded newspaper but i had to clean daily. how often you have to clean the cage will depend on the number of rats. with just two rats i cleaned mine twice a week because of my allergies.
there are tons of rat forums and websites online.
http://www.afrma.org
http://www.petrats.org/
***my ALL TIME fav rat site EVER***
http://www.dapper.com.au/
http://www.ratpalace.com/
http://ratsrule.com
and these are just a few!
any questions feel free to ask me. i have been a rat mommy for well over seven years!
