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The aim of this study was to evaluate the effects of polyculture of the sterlet (Acipenser ruthenus) fingerlings with european catfish (Silurus glanis) (20 – 30%) into recirculating aquaculture system on growth dynamic of the fish and tank’s bioproductivity. Two variants of polyculture have been tested during a period of 42 days in duplicate: V1-sterlet with 20% catfish (600 sterlets and 120 catfish); V2-sterlet with 30% catfish (600 sterlets and 180 catfish). The control group (C) contains sterlet in monoculture (600 sterlets). After 42 days of polyculture of the sterlet fingerlings with catfish 20% (V1) or 30% (V2) there were no significant differences (p>0.05) in sterlets’ growth dynamic among the three variants. The bioproductive indices were better in the polyculture variant where sterlets were farmed with 30% catfish. Polyculture of catfish and sterlet could be a good way to positively influence the fingerling sterlet farming in RAS, having a beneficial impact on tank’s bioproductivity. A significant plus of fish biomass (catfish) resulted by means of valorisation of the unconsumed food by the sterlet, was obtained in both polyculture variants. [ABSTRACT FROM AUTHOR]

The pikeperch farming in recirculating aquaculture systems (RAS) has a relatively short history, and many ideas for production improvement in this species recently emerged. The polyculture is one of these. The aim of this study is to evaluate if sterlet as polyculture species reared in RAS with pikeperch could have a beneficial impact on tank's bioproductivity and growth dynamic of the juvenile pikeperch. One control (monoculture) (C) and two polyculture variants have been established in duplicate: 1335 pikeperch, 45 days old /m³ with 10% (V1), and 20% (V2) sterlet. The experiment has been carried out during 35 days into a RAS with 6 tanks (1 m³/tank). The fish were fed in all tanks with dry food, 10% of pikeperch biomass in each tank daily, assuring ad libitum feeding. A significant plus of fish biomass resulted by valorisation of the pellets unconsumed by the pikeperch, in both experimental variants (V1, V2). The pikeperch reared for 35 days in polyculture with 20% sterlet (V2) had significantly higher body weight than the pikeperch reared with 10% sterlet (V1) or in monoculture (C). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The aquaculture of the sturgeons from the Danube River basin is a niche approached by more and more Romanian entrepreneurs. The sterlet (Acipenser ruthenus) is a fresh water sturgeon with some useful characteristics that recommend this species to become a good candidate for intensive aquaculture in RAS. The monitoring of the growth dynamic of the sterlet or any other fish species reared in controlled conditions is very important for the fish farm management, especially for setting and adjustment of the technological parameters that directly influence the growth performances. The aim of this study is to evaluate the correlations and functional dependencies between some morphological traits, like total and standard length, maximum body depth and body weight in sterlet fingerlings reared exclusively into recirculating aquaculture system (RAS). Our results clearly demonstrated that any of the four body measurements (total length, standard length and maximum body depth and body weight) could be monitored in sterlet fingerlings, to accurately assess the growth dynamic, the correlations among these being very high (ranging from 0.982296 to 0.999778). Moreover, the dependencies of these traits are very high. Three of measurements could be calculated based on sterlet body weight with our equations. [ABSTRACT FROM AUTHOR]

Pikeperch (Sander lucioperca) is one of the most appreciated fish species found in many European countries, in natural waters and in fish farms as well. This species started to be reared into recirculating aquaculture systems (RAS) in the last decade, but the farming technology has to be improved continuously in order to increase the fish production and to reduce the production costs. The aim of this paper was to reveal the preliminary data of a study regarding two polyculture variants of the pikeperch, with European catfish and with sterlet, in order to emphasize the best candidate species for polyculture in RAS. The pikeperch and sterlet fingerlings used in our study have been obtained in RAS, in the spring of the year 2017, from broodfish exclusively reared in RAS. When the study starts, the fish were 6 months and 5 months old, for pikeperch and sterlet, respectively. The European catfish fingerlings have been obtained through artificial method using broodfish from ponds, and reared in RAS until the age of 4 months, when our study starts. The RAS used for the fish rearing had four tanks, with 1 cubic meter of water each. Two variants of polyculture have been tested in 2 replicates: pikeperch with sterlet, and pikeperch with European catfish. The fish biomass of the additional species represented about 21% from the pikeperch biomass in each variant. The fish were fed with dry feed SUPREME-10, size 3mm (Coppens International, Nederland), the amount being calculated as 2.5% from pikeperch biomass in the first 2 weeks, and then reduced at 2% from pikeperch biomass. The main body traits (total length, standard length, maximum high and body weight) were measured at the beginning of the study, and afterwards at every 14 days covering the period of this preliminary study. Based on the data obtained after the measurements, the main bio-productive indices like Weight Gain (WG), Specific Growth Rate (SGR), Daily Growth Rate (DGR) and Feed Conversion Ratio (FCR), have been calculated. The results revealed that both species used in our study as secondary species in polyculture with pikeperch, have been suitable and led to a better valorization of the feed into RAS, but the polyculture of the pikeperch with European catfish seems to be more advantageous. Anyway, our study must go on for a better understanding of all aspects linked to these polyculture formulae used for pikeperch farming in RAS. [ABSTRACT FROM AUTHOR]