We recently had a little excitement at our house when we realized that there were some baby fish in our aquarium. One orange platy shows in the centre of the first photo, and one yellow one is visible in the bottom right of the second photo:
Since platies breed like guppies, we were careful to buy two females from the fish store. However, since they were being housed in a mixed tank with males, it was too late for them. Apparently they can, from a single mating, store sperm for up to six batches of babies. We counted five from this batch (although we may be down to three now), so hopefully that doesn't mean we'll have sixty babies before they run out. Tiny fish are fun the first time, but it might lose its charm the tenth time.
To relate this post to gardening, the water that you take out of the aquarium when you change it makes an excellent, low-strength fertilizer for plants. Since I started using it, my houseplants grow!