New species for freshwater aquaculture: preliminary results on small cyprinids rearing.

Italian freshwater fish farming is dominated by the production of salmonids, in particular rainbow trout. During the last decade trout production in Italy declined steadily for various reasons and trout farmers might be interested in the domestication of new species. Diversification is well studied for Mediterranean marine fish farming but not yet for freshwater one. In this scenario, it may be possible to establish new cold water adapted species for a niche market. The key aspects to be considered for introduction of new species are economical (production costs and market demand) and biological (easy adaptation to rearing conditions, endemic species, etc.). Vairone Telestes muticellus (Bonaparte 1837) and bleak Alburnus alburnus alborella (De Filippi 1844) are two small cyprinids that seem to be potential candidates for diversification in North Italian fish farms. Their feeding and social habits, being not strictly predators and showing strong gregariousness, can facilitate the adaptation to captive rearing and domestication processes, too. Moreover, they are reophilic, moderately cold freshwater fish and autochthonous in the Po valley basin. Market potentials may be both consumption as food and as live bait for anglers. The aim of this study was a preliminary evaluation of the adaptability of vairone and bleak to captive rearing conditions and to an artificial diet. After two months of adaptation to experimental conditions, 95 specimens of vairone and 39 bleaks (mean body weight 0.52 g and 0.63 g, respectively) caught from the wild were stabulated in two 1m x 1m, 150 l tanks, supplied with well water (Temperature: 11.5±2.0°C; Dissolved oxygen: 10.8±0.5 mg/l; pH: 8.04±0.12; TAN: 0.02±0.01 mg/l; NO2: <0.02 mg/l) A practical diet was formulated for both species according to carp nutrient requirements (dry matter 93.6%, crude protein 38.5%, crude lipid 12.0%, crude fiber 0.3%, ash 7.4%). To make the feed suitable to all fish sizes, the dry pellets were crumbled and sieved in particles size range of 0.5-2.0 mm. Experimental diet was offered in a single daily meal to apparent satiety. Both fish species showed good adaptation to captive conditions over 91 days of rearing. Observed mortality was low for a wild species kept in captivity (5.3% for vairones and 7.7% for bleaks). The artificial diet was well accepted by both species and the final mean weight was 0.57g for vairone and 0.73 g for bleak (weigh gain 11.9% for both species). Preliminary results point out a positive reaction to captivity and good tolerance to artificial diet. The observed performance stimulates further investigations on specific diets and rearing conditions in order to achieve optimal growth.