Zur Psychologie des Fisch-Schwarmes

Von Frisch introduced an injured minnow to a school of the same species and watched the result. First, the school approached the wounded fish. Then panic. The fish scattered in terror at something invisible. He called the substance 'Schreckstoff'—fright stuff—and spent years proving it was a chemical released from damaged skin that triggered the alarm.

The discovery revealed something profound about information in biological systems: warning signals can be involuntary. The injured fish doesn't 'decide' to warn others—its torn skin releases a chemical whether it 'wants' to or not. The signal is honest precisely because it cannot be faked: you can only produce Schreckstoff by actually being injured. This is costly signaling taken to its extreme—the signal costs the sender its life.

64% of all freshwater fish species belong to the Ostariophysi superorder that uses this alarm system. For 86 years, the exact chemical remained unidentified. In 2024, researchers at RIKEN finally isolated the molecules—two separate substances called 'Daniol sulfate' and 'Ostariopterin' that must both be detected to trigger the flight-or-freeze response.

For organizations, Schreckstoff illuminates when alarm signals are credible. Whistleblowers who suffer retaliation send honest signals—their career damage proves they're not gaming the system. Anonymous complaints carry less weight precisely because they cost nothing. The fish principle: if warning someone doesn't hurt, the warning might not be real.