There are 52 species in this order of fish, divided among four families. The fish in this order are usually small and silvery, and they live in cold oceans as well as freshwater habitats.

Many Osmeriformes have slender, streamlined bodies, forked tails, and a small extra fin on their backs called an adipose fin. This fin is soft and fleshy, unlike their other fins, and can help with swimming stability.

Osmeriformes are mostly found in the Northern Hemisphere, especially in cold coastal waters, rivers, and lakes. Some species spend most of their lives in the ocean but swim into freshwater streams to lay their eggs. This journey is called a spawning migration and is important for reproduction.

These fish play a key role in aquatic food webs. They eat tiny animals like plankton and small crustaceans, and they are an important food source for larger fish, birds, and marine mammals.