Sushi, anyone?

I was out of town for a long weekend and had my flatmate feed my fish while I was gone. All four are still alive, so she did an exemplary job. However, we still had some issues when I returned on Sunday night. I opened the tank to discover...

fish babies.

My fish are only about an inch long and 1/4-inch wide, so these babies look like black specks with tails, not too big, but far too many to count. In addition, one of my plants had green webbing I mistook for algae but now believe was the net/sac that fish are hatched in.

I swapped out some water, about a gallon of the 4-5 the tank holds, and with it dumped out some of the baby fish. If I can barely see them in the water they don't count as living creatures. I'm not sure what to do about the babies, really, my tank isn't big enough for more fish, and the net I have is too big to catch the babies. The only thing I can think to do is not feed my fish for a few days. Hopefully they'll get hungry enough to eat the young'uns.

Meanwhile, I'm not sure what to do to prevent my fish from having sex. I doubt my flatmate did anything out of the ordinary that would excite the fish, except that their light was on all weekend. Maybe the warmer water makes for good breeding conditions? which I doubt, the websites I've found suggest cooler water.

On the other hand, I know the spawning happens, and I guess it's a sign of good health. Hopefully most will die off, though some suggest that it's a good way to keep the population sustained, as the lifespan isn't very long. That said, I still have an original fish from 20 months ago. Another site says the lifespan for these little guys is 3-10 years. Yikes.