Everything you need to know about the beluga sturgeon: biology, status, and why it doesn’t belong in the garden

The name “beluga” evokes the world's most expensive caviar and fish the size of a boat. Yet it sometimes appears in garden centres, in the form of juveniles around twenty centimetres long, alongside sterlets. Before giving in to temptation, you need to know what animal you are dealing with. The beluga (Huso huso) is the largest of the sturgeons, a migratory predator that lives for a very long time and matures very late: it is a fascinating species, but not a garden-pond fish.

Identity card of the largest sturgeon

Sturgeons form a very ancient family of fish with largely cartilaginous skeletons, covered in rows of bony plates called scutes. The beluga is its largest representative. Specimens several metres long and weighing more than a tonne were reported in the last century, although current catches are much smaller due to the lack of old fish.

A migrant of the Caspian and Black Seas

The beluga spends most of its life at sea, in the basins of the Caspian and Black Seas, and travels up major rivers such as the Volga, Ural, and Danube to spawn over gravel beds. It is described as anadromous. Dams have cut off much of its migration routes, and the Adriatic population is considered practically extinct.

Unlike most sturgeons, which search the mud for worms and larvae using their barbels, the adult beluga hunts. Its wide mouth allows it to swallow whole fish. Juveniles start with invertebrates, then gradually switch to a fish-based diet.

A species that lives a long time and reproduces late

The entire beluga's plight stems from this biological trait. A female typically takes around fifteen years, or even longer, before spawning for the first time, and then does not reproduce every year. A fishery that removes large fish for their eggs therefore removes precisely the individuals that ensure the population's future. The species is classified as critically endangered by the IUCN, and the trade in all sturgeons is regulated by CITES.

This is also why almost all juveniles sold come from farms, and why some fish marketed as "beluga" are actually hybrids, such as the bester, produced by crossing beluga and sterlet. Always ask the seller for the exact origin.

Why the beluga is unsuitable for a garden pond

A juvenile beluga is a beautiful, calm fish that patrols the bottom like a small shark. The problem emerges over time. In well-fed captivity, this species grows quickly and soon exceeds the dimensions of an ordinary pond. A large fish circling in a few cubic metres eventually becomes injured, stressed and poorly oxygenated.

There is also a second point, often overlooked: an adult beluga eats fish. In a pond populated with goldfish, shubunkins or young koi, its presence is not inconsequential. Finally, like all sturgeons, it swims poorly backwards and can easily get stuck in corners, dense plants or pump intake screens. A common case: a sturgeon found trapped against an inadequately protected intake grate.

Oxygen and temperature: requirements shared by all sturgeons

Sturgeons live near the bottom, in cool, moving water. They do poorly in warm, oxygen-poor water, whereas koi carp tolerate it better. In summer, when the surface temperature stays above 25 °C, a poorly circulated pond becomes a trap: dissolved oxygen decreases as the water warms, and the bottom, where the sturgeon lives, is often the most oxygen-poor area. Bottom diffuser aeration, a properly sized filter and some shade make a real difference.

Another precaution: many pond treatments carry a warning that they are incompatible with sturgeons. Before adding anything to the water, read the instructions all the way through.

The sterlet, the sensible alternative

If you dream of owning a sturgeon, the sterlet is the most suitable species for a large garden pond. It remains a size compatible with a pond of several cubic metres, lives entirely in freshwater, and feeds on invertebrates and sinking food. Nevertheless, it requires a clear bottom, well-oxygenated water, and specific food, as it does not rise to the surface to compete with koi for floating pellets.

Also read

To install a suitable sturgeon in your pond: Sturgeons in a pond: a micro-guide by the Foudebassin experts.

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Frequently asked questions

— How large can a beluga sturgeon become?

In the wild, several metres. Specimens weighing more than one tonne have historically been reported. It is the largest of the sturgeons.

— What does a beluga eat?

Young fish eat invertebrates, while adults mainly eat fish. This is a major difference from the sterlet, which remains an invertebrate feeder.

— Can you put a beluga in a garden pond?

It is not recommended: it grows quickly in captivity, becomes too large for an ordinary pond, and may attack other fish. The sterlet is more suitable.

— Why is the beluga threatened?

It reproduces very late, its migration routes are blocked by dams, and it has been overfished for its caviar. It is classified as critically endangered by the IUCN.

In summary

• The beluga (Huso huso) is the largest of the sturgeons, migrating between the sea and rivers.
• As an adult, it feeds mainly on fish, unlike the sterlet.
• Its very late maturity explains its vulnerability to fishing: it is critically endangered.
• In a garden pond, it quickly becomes too large; the sterlet is the sensible sturgeon for a pond.
• All sturgeons require a clear bottom, cool, well-oxygenated water, and sinking food.

Last updated: September 29, 2026.