Early development and growth of sterlet [acipenser ruthenus) in the CZECH REPUBLIC

Growth rate of sterlet larvae and juveniles during 2008 and 2009 was studied under experimental and farming conditions in the Czech Republic. The embryos hatched when reaching a mean total length (TL) of 9.0 mm. Larvae were fed by living food,with a gradual transition to dry diet. The exogenous feeding and the larval period of ontogeny started at DAH 9 (day after hatching) reaching TL of 15- 17 mm accompanied by melanin plug exclusion. Towards the end of larval period (DAH 39-43,TL 50-58 mm),the embryonic finfold disappeared and the formation of fin apparatus was nearly completed. During the larval and early juvenile development,daily increments of TL and weight (w) ranged between 0.33-4.23 mm.d-1 and 0.0018-1.6400 g.d-1,respectively. The specific growth rate (SGR) ranged from 25.65 to 2.73 %.d-1. Growth intensity and length parameters are similar to the Starry sturgeon,lower than those of the Siberian sturgeon and Russian sturgeon and significantly lower than at Beluga sturgeon. Sterlet s Fulton weight condition factor (FWC) was higher than in the Siberian and Starry sturgeon. The development was also observed on the basis of morphological changes. The larval development could be divided into six steps.