A comparative study of different preparations of decapsulated Artemia cysts as food for tench (Tinca tinca L.) larvae

Two 30-day experiments were conduced to evaluate different preparations of decapsulated Artemia cysts as food for tench larvae from the onset of exogenous feeding or after an initial period feeding on live nauplii. In the experiment 1, four dietary treatments were tested: Artemia nauplii-only (control group), nauplii for the first 7 days and fresh cysts thereafter, nauplii for the first 7 days and brine cysts thereafter or nauplii for the first 7 days and dried cysts thereafter. The same feeding treatments were replicated in experiment 2, but fresh, brine or dried cysts were supplied from the first day of exogenous feeding. In overall, survival was high. Tench larvae fed decapsulated cysts had higher growth (P<0.001) and lower food conversion ratio (P<0.001) than larvae fed live nauplii only. The highest growth (19.2 mm TL, 88.7 mg W, 18.33%/day SGR) was achieved with fresh cysts from the onset of exogenous feeding. The relation between the behaviour of the different preparations of cysts in the rearing tanks and their suitability for tench larvae is discussed. Both fresh and brine cysts are a suitable food from the onset of exogenous feeding and dried cysts can be successfully used after 7 days feeding on nauplii.