Most of sturgeon species are threatened and many populations rely on stocking practice. Within this subject, the quality of the fish produced is a key factor to success and reliable methods to evaluate fitness-related traits are needed. Moreover rearing practices are known to act on juvenile performance and environmental-enriched rearing can be promising. Acipenser sturio is critically endangered and the last wild population originates from the Gironde basin (South West of France). Since 1994, no reproduction in the wild was observed and a captive stock was constituted. In the Gironde, after one attempt in 1995, regular stocking occurred since 2007. Since then, more than 1.5 million individuals were released at different stages and the population is regularly monitored since 2009. The rearing of those juveniles before release mainly corresponds to common hatchery practices for sturgeon production. With the goal to understand and improve the post-release outcome of those fish, we got interested in the evaluation of fish performance that could be linked to fitness: survival, growth and behavior. Within behavior, several aspects can be involved in fish survival such as abilities to feed on live or novel preys, to detect or avoid predators or to explore new environments. Between 2011 and 2013, to evaluate those abilities we proposed some methodologies using different setups. Mainly fish reared under traditional conditions were tested and we highlighted a high inter-individual and inter-annual variability; thus some relevant behavioral tests were selected. In 2014, some fish were also reared in enriched environment and their performance was compared according to the rearing practice. Positive effects of enriched environment conditions on growth and exploratory behavior were highlighted and possible genotype-environment interaction in favor of enriched practice as well. Further implementations of rearing practice are proposed for the future.