The polyculture of sterlet (Acipenser ruthenus) and carp (Cyprinus carpio) in recirculating aquaculture systems. the effects on fish growth dynamic and production.

The polyculture of two or more fish species is very common in ponds, this fish culture technique being relatively newly applied in recirculating aquaculture systems (RAS). The aim of this study is to evaluate the effects of polyculture of the sterlet (Acipenser ruthenus) and common carp (Cyprinus carpio) (30-60%) into recirculating aquaculture system on growth dynamic of the fish and tank’s bio-productivity. Two variants of polyculture have been tested during a month in duplicate: V1 - sterlet with 30% carp (200 sterlets and 60 carps/ 1 m3 tank); V2 - sterlet with 60% carp, (200 sterlets and 120 carps/1 m3 tank). The control group (C) contains sterlet in monoculture (200 sterlets/ 1 m3 tank). The polyculture for 28 days of the sterlets with carps 30% (V1) or 60% (V2) did not significantly (p>0.05) influence the sterlets’ growth dynamic. Bio-productive parameters were better in the polyculture variant where sterlets were farmed with 30% carps. Polyculture could be a good way to positively influence the fingerling sterlet farming in RAS, having a beneficial impact on tank’s bio-productivity. A significant plus of fish biomass (carp) resulted by valorisation of the pellets unconsumed by the sterlet, was obtained in both polyculture variants.