I raised a bunch of them from the wee size of about 1 cm at work. When they grew up, I took 7 of them home to my aquarium. When they matured, the males started getting really randy and chasing the females while displaying. The guys would splay all their fins and do a little shivering dance.
You can tell the males from the females because they have a slimmer body (especially if the females are gravid). While I haven't had caviar yet, I noticed the behavior was "worse" when I separated them from the community tank. Well, it got so bad, to the point of being aggressive, that I gave away 4 of them. Being left with 3 (1 male, 2 female) the minnows have calmed down considerably.
These are very hardy fish that can tolerate just about anything. They've gone through ammonia spikes, high summer temperatures, heater malfunctions, and are still going strong after 3 and 1/2 years!