you can put just one male and one female in the tank together. it is better to have a male and 2 or more females. sometimes fish just dont match up but you should still get a pair. to increase your chances of getting a pair i would get a regular colored male and an albino female. the male chooses who he wants to mate with. i had 3 females in the tank with no males and when i finally put 2 males in the females went crazy over them. the females dont care about which male they get as long as he is healthy and large enough. the male is the one who chooses. the male will choose the female with the brightest red belly. the red belly stands out more on albino females so males are more attracted to them.
you can tell the difference between males and female fairly easily. the females have a more vibrant red belly and their bellies are much more round. the males are more torpedo shaped and are larger. the males also develop pointed dorsal fins.
kribensis will eat pretty much anything. i have fed them brine shrimp(live and frozen), blood worms, pellets and algae wafers. they will eat the zucchini i put in for my angels, plecos and SAEs.
they are not expensive and have great personalities. kribensis are great parents. they will protect their fry very well. the mother will take them on excursions for the day while the father swims higher up to make sure no other fish get too close.