In May of 2014 (it's a long story) we added 5 feeder fish to our pond. The 3 adult koi were totally unimpressed as the feeders immediately disappeared behind the rocks not be seen again for several weeks. When they did reappear, there were only 4. Until last week, that is, when an undersized goldfish came swimming out from between the rocks. It's not confident enough to take it's place, making only brief appearances, but in a week or two it'll be chasing around with the other 4.