Last night I was checking out my tank and a little after the blue light turned on I saw my pair of spotted mandarins chasing each other around on the rocks. So I grabbed a chair and watch them......after a few minutes they were swimming next to each other all the way to the surface and once they hit it they released eggs and sperm!!! I couldn't believe it because they are still fairly small and I only got them approximately 6 weeks ago but looking closer at the female she had a big round belly!!!