The experimental rearing of tench (Tinca tinca) juveniles of two size classes with initial individual weight of 0.8 and 1.2 g was performed into flow-through aquaria connected to recirculation system during a period of 63 days. Three feeds (KARPICO Supreme 7 Ex, ASTA 2, L05/CH) with nutrient content of 37/8, 42/7 and 35/7 (% proteins/ fat) were used in the experiment. Achieved values of production indicators – feed conversion ratio (FCR) and specific growth rate (SGR) ranged from 1.84 to 4.15 and from 0.70 to 1.49 %.d–1, respectively in relationship to the size class and feed used. More favourable values were achieved with the bigger size class regardless to the diet used (FCR 1.84–3.53 and SGR 0.83–1.49 %.d–1) and the best results were achieved when using ASTA 2 feed (2.05 and 1.84 or more precisely 1.36 and 1.49%.d–1).

Growth rate of sterlet (Acipenser ruthenus) juveniles and adults was studied and compared with other sturgeon species under experimental and farm conditions in the Czech Republic. During the juvenile development (0+ to 5+) the specific growth rate (SGR) decreased successively from 17.67 to 0.05 %.d−1. During the adult period of development (6+ to 13+), the SGR fluctuated from 0.0191 to 0.0562, mean = 0.0410 %.d−1. In addition, body weight condition and length-weight relationship are presented. The adult period commenced at average age from 4 to 5 years. At the end of subsequent 13 years of life (1st–13th), following values of TL/w (in mm/g) in reared sterlet were determined: 250/53, 350/174, 400/250, 440/320, 465/400, 490/462, 516/525, 546/645, 561/720, 596/860, 610/1014, 625/1199, 660/1456. A very fast growth intensity was determined in the young sterlet (1st and 2nd year) while it decreased in the older fish. Growth intensity of other reared greater sturgeon species (Huso huso, Polyodon spathula, A. gueldenstaedtii, A baerii, A. stellatus), compared with sterlet in early juvenile period of ontogeny, were mainly higher.

CILEČEK, M., BARÁNEK, V., VÍTEK, T., KOPP, R., MAREŠ, J.: Production eff ect of diff erent commercial feeds on juvenile tench (Tinca tinca L.) under the intensive rearing conditions. Acta univ. agric. et silvic. Mendel. Brun., 2011, LIX, No. 6, pp. 93-98 Feeding experiment with juvenile tench was focused on evaluation of production eff ect of three diff erent commercial feeds with diff erentiated level energy and protein (Karpico Crumble Excellent Ex, Dan Ex 1352, Pro Aqua Brutfutter). In the 42-day experiment at 26 °C, commercial starters were fed intensively to tench of initially 18.92 mm mean total length and 69.41 mg individual mean body weight. Main monitored indices were -survival rate (%), individual body weight (mg) and specifi c weight growth rate (%.d −1 ). The best result was achieved with commercial starter Pro Aqua Brutfutter -mean individual body weight 483.38 mg, specifi c weight growth 4.44 %.d −1 and survival 99.1 %. Increasing level energy and protein increased production parameters of juvenile fi sh. starter's feed, feeding, juvenile tench, fi sh breeding, Artemia salina nauplii The tench (Tinca tinca L.) is species of great interest in Europe aquaculture. In the Czech Republic tench is traditionally reared in the fi shponds since the 11 th

Conversion success of pond-reared zander (Sander lucioperca) fry was evaluated using three different converting methods: direct conversion to dry feed (Bio-Optimal Start 0.8 mm; variant A), three–day application of semimoist feeding mixture on the base of fish (variant B) and three-day application of semimoist mixture + three-day co-feeding of semimoist mixture and dry feed (variant C). Two replicates per treatment were applied. These three methods were evaluated regarding specific growth rate (SGR), condition coefficient (K), survival and cannibalism. Mean initial total length (TL) of fish was 35.22 ± 2.15 mm and mean individual weight (w) was 0.31 ± 0.05 g. There were 600 individuals in each circular tank. The initial stock density was 2 fish.l – 1. Fish survival during a 14-day period of rearing ranged from 34.33 % (variant C) to 50.33 % (variant A). Significantly (P < 0.05) better conversion performance was achieved with variants A and B than with the variant C regarding all parameters.