I noticed after baby angelfish hatched that their parents often laid additional eggs immediately afterward. This stumped me because if I was in their shoes - uh, fins - and I had 200 babies swimming around, why would I want 200 more?
Then I realized the parents were laying the additional eggs as a food source for the babies. I watched as the babies ate the eggs and the parents swam around, as if encouraging them.
I thought it was very interesting that the parents would come up with this ingenuous food source. Talking about growing your own!