[6][7] Juveniles have a flattened and triangular rostrum, with a distinctive colouring on the back, dark brown with wide paler areas casually distributed.

[13] During spring months mature fish migrate to the upper part of the rivers, then they lay eggs from April to June[14] in deep and oxygenated waters, on gravelly substrates at a depth of 2–10 m (10–30 ft),[15] with a current velocity of 0.8 m/s (2.6 ft/s) at least.

[17] The eggs adhere at the substrate and hatch after about a week, fry are about 8–10 mm (0.31–0.39 in) long with pelagic attitude like other sturgeons, then after ten days they begin to be demersal.

[8] Adriatic sturgeons tend toward an opportunistic feeding, swallowing substrate together with prey and organic matter, including small decaying carrions.

[19] In both cases, the analysis of the digestive tract revealed a high presence of inorganic matter (sand, silt, mud, etc., even plastic) mixed with food.

The typical habitat of A. naccarii are large, deep rivers with strong current, which flows in the Adriatic sea, mainly in its north-western portion.

[21] However, despite some A. naccarii have been captured in the Adriatic Sea, it has been shown that this sturgeon tolerates with difficulty high salinity for extended periods, spending short periodsin marine environments for foraging activities.

[23] Furthermore, it has been shown, tracking the movements of tagged fish in some cold and oxygenated rivers of northern Italy (Piave, Sile, Livenza), that A. naccarii regularly moves to areas where the salt intrusion from the sea involves an electrical conductivity of 1000–4000 μS in the water (about 0.6–2.5‰ salinity at 18 °C (64 °F)), on equal terms of other environmental variables.

[1] However, a number of organisations are concerned in attempts to preserve this species and a captive breeding scheme has been established, with young microchipped fish released into the wild[1] officially since 2004, following EU projects (Life03nat/IT/000113 and subsequents); before 2004, almost only post-larvae and very small sturgeons were released (since 1988), at a time when fishing of sturgeons was still allowed in Italy (until 1997) and the allochthonous wels catfish (Silurus glanis) was at the apex of its numerical expansion in Italian rivers, so the survival rate was extremely low.

[25][26] It has been reported by researchers that, despite the release of captive-bred fish, no signs of spawning have been observed in the wild;[1] however, considering that Adriatic sturgeon needs at least twelve years to attain sexual maturity and matures gonads in alternate years, and considering the release of captive small fish started in 2004, it was probably premature to look for wild fingerlings at the time of the publication of the report (2011).

[23] In the recent past catfish anglers caught, filmed and released mature specimens of Adriatic sturgeon in the Po and other rivers, also very large, old fish (for example, [1], [2],[3]).

[citation needed] The capture of juveniles without microchips, smaller than those released into the wild by researchers and authorities, is an indication that Adriatic sturgeon naturally spawned in Italian rivers.