and if you get Kribs, make sure you have lots of caves and plants for them to hide in. when i first owned Kribs a few years back, i made the mistake of buying a pair of males. i thought i had gotten a male and female. and the petstore clerk sent me home with a pair of kribs and ONE rock cave. he said they just needed a cave to hide in.
the next day, i had to return one of the male kribs. he was quite beat up too, fins all tore up and his tail was nearly gone! the petstore manager apologized and gave me a female and another cave for free.
you can have more than one male, just make sure you have more than one cave....i learned that lesson the hard way!

and dont have 2 males and one female, they'll fight over the female.
my lfs sells kribs, usually they're really small. only about an inch long. and they cant always tell if they're male or female yet, but if you find out that you dont have a breeding pair, you can swap them out for other kribs until you get a breeding pair. or whatever you want, all females, all males...my lfs is pretty cool about that.