It is ubiquitous throughout much of Eurasia, from Britain and Spain to eastern Siberia, predominantly in cool (12–20 °C (54–68 °F)) streams and well-oxygenated lakes and ponds.

[2] The back is normally brownish-green, and is separated from the whitish-gray underside by the lateral stripe or blotches described above,[3] The common minnow is found in northern Eurasia from Ireland in the west and in the east to the Amur drainage and Korea.

[2][3] The common minnow is found in a wide variety of environments that have cold, well oxygenated water, often in syntopy with salmonids.

These include small streams with fast currents, and, in the more northerly parts of its range, large lowland rivers.

For spawning, it requires clean gravel areas in well oxygenated flowing water or where waves wash on lake shores.

It also needs deep pools with low current to overwinter in, and these must have a coarse substrate among which the fish can hide.

[1] Shoaling and schooling behavior of common minnows occur early in their development, as soon as they become capable of swimming.

[6] The group formation of common minnows can be explained by the selfish herd effect proposed by W.D.

The chemical, named Schreckstoff after a German word meaning "fear substance" by Karl von Frisch who first described it, is contained in specialized skin cells called alarm substance cells and is released from an injured or killed minnow.

[9] The apparent altruistic behavior is not clearly understood, because the likely explanation of kin selection is not supported by the shoal structure of common minnows in which shoalmates are not necessarily closely related.

Only the naïve common minnows reacted to the signal by relocating themselves to the central position in the group.

The observation shows that common minnows can detect the predator's impending aggressiveness and motivation to attack.

[14] Different populations of common minnows show varying degrees of anti-predatory activities.

[15] Some components of anti-predator activities are inherited, as indicated in the early emergence of shoaling behavior in laboratory-raised immature minnows.

In general, a larger shoal of fish locates food faster, which was confirmed to be true in common minnows.

They tend to associate with familiar shoalmates [18] and prefer to form shoals with poor competitors for food,[19] which indicates that they can recognize individual conspecifics.

Common minnows tend to associate with familiar shoalmates, but new alliances can form when different groups encounter.

Clean water helps and so do plant life and general good quality aquarium conditions.

First of all, the difference in the shades of colour on the fish become stronger (dark gets darker, light gets lighter), and the fins, throat and some other areas redden.

It is very important to have much plant cover for the fry to hide in as the adult fish will try to eat them especially if underfed and if not much other live food is given.

There will be many tiny white dots in the water which, if looked at under a microscope reveal to be many types of infusoria in their millions.