Canadian researchers have identified the first species of toilet-trained fish - pikes select secluded areas to deposit their faeces to safeguard against being detected by their prey (New Scientist, Vol 146, No 1976).

When pikes attack fat-head minnows, the victims release an alarm pheromone that alerts other minnows to keep away. Researchers Grant Brown, Douglas Chivers and Jan Smith of the University of Saskatchewan showed that the pheromone can even survive the journey through the pike's intestines.