The effect of alarm substance on predation among cyprinids

1. 1. Three experiments investigated whether predation among cyprinids is reduced by alarm substance. 2. 2. In the first and second experiment large roach and large minnows respectively chased and swallowed small roach without an alarm reaction. 3. 3. In the third experiment blinded minnows showed an alarm reaction after the introduction into their tank of water out of a tank in which a pike had swallowed a small roach, whereas they did not react to water out of a tank in which a large minnow had swallowed a small roach. 4. 4. The results do not support the view that one of the functions of alarm substance is to reduce intraspecific predation among cyprinids. It is doubtful whether such a predation is detrimental to the survival of the species