Is there a fish alarm pheromone? A wild study and critique

In 1938 von Frisch reported that European minnows, Phoxinus phoxinus, displayed a marked fright reaction to conspecific skin extract. This was attributed to the presence of an alarm substance or Schreckstoff. Later, Schreckstoff was viewed as a classic example of an alarm pheromone. However, Williams (1964, 1992) argued that there are considerable problems in explaining the evolution of an alarm pheromone of this type, and, despite being the focus of extensive research, there have been few attempts to examine the function of Schreckstoff under natural conditions. We show that, contrary to expectation, wild European minnows fail to modify their behaviour or leave the area when exposed to skin extract. These results indicate that the minnow fright reaction is context-dependent and cast further doubt on the hypothesis that Schreckstoff is an alarm pheromone.