Effects of stocking density, feeding technique and vitamin C supplementation on the habituation on dry feed of pikeperch (Sander lucioperca) pond reared juveniles

Influence of three different stocking densities, vitamin C supplementation of Daphnia spp. and feeding practice (i.e. mechanical, hand) on the success of dry feed habituation of pond reared pikeperch juveniles was investigated through one month trial. Pond reared pikeperch juveniles were harvested 42 days post-fertilisation (mean individual weight 1.1 ± 0.3g) and stocked into the experimental recirculation system. For the stocking density trial, fish were stocked in three different initial densities of 0.5, 1 and 1.5 fish L-1, while the trial on live food supplementation and feeding practice was performed with two two-group comparisons with one common control treatment. All treatments were performed in 3 replicates. Analysis of variance did not reveal any significant differences in the assessed parameters between the tested stocking densities. However, Pearson correlation for the habituation success was strong in the course of increased density (r2 = 0.829, p = 0.006). Vitamin C supplementation led to increased survival, habituation success and growth, although the differences were not significant (p > 0.05). Similarly, there were no significant differences between the hand and mechanical feeding in the habituation success (p = 0.860). Based on the results of present study and previous results reported for habituation of pikeperch and walleye pond nursed juveniles, stocking densities of 4 to 8 fish L-1, feeding with dry feed with worms supplied manually and possible enrichment  with vitamin C of the given food could be suggested for the successful commercial pikeperch dry feed habituation.