I came home to find my threadfins in the mood! My dominant male, and to a lessor extent, some of my other males, were turning a deep gray, with a silver stripe down their forehead and they were flaring continuously. This happened a few times- they turned colors so quickly! I don't know if I'll be seeing any fry or eggs about, as they don't usually survive in a community tank, but they're mop spawners, and I have lots of java moss, so I guess we'll see. I snapped some pics because I thought the behavior was so interesting.
My rainbow yesterday:
His forehead all stripey:
Flaring like crazy, he would stop dead in the water like this for upwards of 30 seconds: