Every day at dawn he makes the rounds of the ponds, and sees whether or not the fish are "sticking their heads out of the water." If they are, they are either sick or there's not enough oxygen in the water. If it's the latter they have to turn on the water wheel and add oxygen.
像養殖場的吳天詳，每天清晨就先巡視魚塭，看魚是否「浮頭」，若是浮起頭，不是表示生病，就是氧氣不夠；若是後者，須再加水車打氣。