They'll make a number of false ascents together, rising to the surface of the water, breaking apart and swimming down, and coming back together to repeat. Sometimes this process takes hours, sometimes only a few minutes. At the last ascent, at the surface of the water both male and female release and the eggs are fertilized and left to drift. They often make a pretty big splash for their size doing that, mine would spray water out of the aquarium
They're called pelagic (broadcast) spawners as all they do is release the eggs and have no further contact with them. The female will go to her sleeping place at that point, the male may continue swimming around for awhile.
The eggs hatch quite quickly, 12 hours or so. The larvae are very tiny like 2mm, they live off their yolk sac for a few days before getting a mouth and beginning to feed on their own.
If there's enough food for them, the mandarins can spawn every night, sometimes even twice a night. It takes a toll on the female though, the amount of energy and oil she needs to put into the eggs is a tremendous drain on her. Mine would spawn best when I fed the female mysis shrimp, a very good food for her to replenish what the eggs took out of her. Despite pigging out all the time though, with them spawning constantly she never grew at all. The male meanwhile got about twice as big.
so sweet. hehe
