This dataset contains all information collated during an experimental mass incubation and rearing of European smelt (Osmerus eperlanus, L.) eggs and larvae. The experiment specifically tested (I) whether a technical modification of the egg incubations jars would improve the overall number of surviving eggs, and (II) how first-feeding protocols for larvae could be improved. For more details please see the associated article Reiser et al (2023) in Aquatic Living Resources. The following parameters were recorded: (1) number of incubated eggs, (2) egg survival, (3) hatch success, (4) length-at-age, (5) larval mortality, and (6) larval prey consumption. Data on all six parameters are provided as separate CSV files. In addition, a legend of the abbreviations used in the CSV files is provided. The code for analyzing the data in R is available upon request. Adult European smelt caught in River Weser (Bremen, Germany) at 53.060 (lat) and 8.864 (long). Experimental rearing at Thünen Institute of Fisheries Ecology (Herwigstr 31, 27572 Bremerhaven, Germany) at 53.524 (lat) and 8.581 (long).