Minnow are small freshwater fish that live in shoals.
Minnow are distinctive in appearance with green to dark olive sides. They have a short, rounded dorsal fin and an upturned mouth. Female minnows have a white shiny belly whereas males have a red belly and red pelvic fins. Sometimes the male minnow can be confused with a three-spined stickleback.
The dark row of scales along the central length of the fish’s body is known as the lateral line.
Common Minnows can communicate with their shoal, if they are hurt by a predator, by using a chemical signal. The chemical, named Schreckstoff after a German word meaning “fear substance” is contained in specialized skin cells called alarm substance cells.
When common minnows sense the alarm substance, they form tighter shoals as individuals move to be in the central position in their shoaling group, where they will be safer from the predator attack.