Common Minnow

Shoaling adjustment in response to predation risk

When common minnows sense the alarm substance, they form tighter shoals as individuals move to be in the central position in their shoaling group. However, in an experiment where common minnows were habituated to the chemical by continuous exposure, common minnows did not react to the signal. Only the naïve common minnows reacted to the signal by relocating themselves to the central position in the group. In another experiment, researchers observed common minnows in semi-natural setting and found that common minnows' shoaling behavior varies depending on the habitat's complexity. Minnows tend to respond to increased predation risk by forming larger shoals in structurally simple habitats and by reducing their rate of movement in complex habitats.