We feed our fish when the plants start to die away and it starts to get cold at night and warm during the day. They are only active when the water warms and since they have nothing to eat it is necessary for flakes or the floating pellets. But then again, a blue heron keeps eating our fish at the end of the summer every year....he didn't get any so far this year. Hehe, we put up some screen door stuff to keep him out...it has worked so far.