Sterlet

Quick facts

Adult size

80 cm, 6000 g typical harvest weight

Days to harvest

1095 to 2190 days from fingerling

Lifespan (max)

up to 25 years

Diet

carnivore

Temperature class

cold-water

Difficulty

advanced

Water parameters

Temperature range

4–22°C (optimum 16°C)

pH

7 to 8.5

Hardness

5 to 25 dGH

Minimum tank

2500 L per individual at harvest size

Feed and growth

Feed protein

45% target

Daily feed (warm water)

1.00% of body weight per day

Daily feed (cool water)

0.50% of body weight per day

Max stocking density

35 g per litre of system water

A 6000g adult eats about 60.0 g of feed per day at optimum temperature. For a roster of 10 fish at adult size, that's around 600 g of feed daily.

Legality

Aquaculture and possession rules vary by jurisdiction and change over time. This table reflects regulations as of the verified date on each row. Verify with your local fisheries or wildlife authority before stocking.

Jurisdictions not listed here default to "check local regulations". A non-listing is not a green light; rules in your specific county or municipality may apply.

Habitat and origin

Native to rivers draining into the Caspian Sea, Black Sea, Sea of Azov, and the Baltic Sea, including the Volga, Danube, Don, Ob, and Yenisei. The species (Acipenser ruthenus) is the smallest commonly cultured sturgeon, reaching 1–1.2 m and 5–16 kg, significantly smaller than Russian sturgeon or beluga. Sterlet are among the few sturgeon species that spend their entire life in freshwater (most sturgeons are anadromous or semi-anadromous). They mature faster than larger sturgeon species: females can produce roe at 5-8 years, compared to 10-15 years for Russian sturgeon. Sterlet caviar is a mid-range premium product ($100-300/kg retail). Wild populations have declined substantially due to river damming and overfishing. The species is the most commonly kept ornamental sturgeon in garden ponds in Europe.

Climate and outdoor ponds

Climate classification

cold-water (cool water required, dies in heat)

Outdoor pond zones (USDA)

3 to 8 (winter low around -40°C or warmer)

Heating in a temperate climate

Not required (handles seasonal cool periods)

Cooling in a temperate climate

Required if your summer water temperatures exceed the upper tolerance

Zone bounds reflect year-round outdoor pond viability with no active heating. Anywhere outside the bounded zone, the species can still be kept in an indoor heated tank or a seasonally-managed system. Verify your specific microclimate, as a sheltered yard zone can run a half-zone warmer than the regional rating.

Care notes

The most practical sturgeon species for smaller-scale aquaponics, thanks to the relatively small adult size and earlier maturity compared to larger sturgeons. Temperature range: 4–22°C, optimal at 14–18°C. Growth on sturgeon pellet (42-48% protein) is moderate: reaching 1–2 kg in 3-4 years. FCR is 1.3-1.8. Dissolved oxygen above 6 mg/L (sterlet are more oxygen-demanding than most fish). Ammonia below 0.5 mg/L. Stocking density in RAS: 15-30 g/L. For meat production, harvest at 0.5–1 kg (2-3 years) is viable; for caviar, females need 5-8 years. The bester hybrid (beluga x sterlet) is also farmed commercially and combines sterlet's smaller size with some of beluga's faster growth. Sterlet are bottom feeders that require sinking pellet; they don't feed at the surface. The mouth is ventral and protrusible, adapted for vacuuming food from the substrate. Tank design should minimize sharp edges because sterlet have soft, scaleless skin that damages easily. Fingerlings are available from sturgeon farms in Europe (particularly Germany, Austria, and Hungary) and from some US sturgeon operations. CITES regulations may apply to international trade. For European aquaponics operators wanting a cold-water species with caviar potential on a shorter timeline than Russian sturgeon, sterlet is the best option.

Further reading

• Aquaponics water chemistry: balancing pH for fish and plants
• Fish for aquaponics: tilapia vs everything else