Survival of Embryos and Fry of Sea Trout (Salmo trutta m. trutta) Growing from Eggs Exposed to Different Concentrations of Selenium during Egg Swelling

SIMPLE SUMMARY: Selenium-poor areas are defined in the Earth. Adequate selenium (Se) consumption enhances the health and growth of organisms, but overdose of it can be harmful and pathogenic. The objective of the study was to investigate Se supplementation effects in the non-feeding stages of fish. Fertilised eggs of sea trout were immersed in water enriched with Se during the egg-swelling period. Se at a concentration from 0.5 to 8 mg Se L(−1) slightly impacted the hatching rate. A higher concentration of Se resulted in declined survival of embryos. Accumulation of Se in the body of hatch increased with the increase of element concentration in the aqueous environment during egg swelling. The survival of fry was similar in all groups, while the fry length and weight correlated positively with Se concentration in its body. In Se-poor areas, immersion of fertilised eggs in water enriched with Se during egg swelling can be used to supplement the deficient element to fish in order to improve breeding outcomes in aquaculture. ABSTRACT: Adequate selenium (Se) availability enhances the health and growth of organisms, but overdose of it can be harmful and pathogenic. The study’s objective was to analyse the impact of short-term exposure of sea trout fertilised eggs to inorganic selenium (SeO(2)) at concentrations from 0 to 32 mg Se L(−1) to find the optimal and toxic dose of Se on early fish development. Se accumulated in the body, embryos’ survival rate, and growth in the first four months of life was examined. Swelling of fertilised eggs in water supplemented with Se at a concentration from 0.5 to 8 mg Se L(−1) was associated with a slightly positive impact on the hatching rate. At higher Se concentration, a harmful effect on the survival of the embryo was observed. The survival of fry was similar in all groups, while the fry length and weight correlated positively with Se concentration in its body. Immersion of fertilised eggs in water enriched with Se during egg swelling can constitute a method to supplement the element to non-feeding stages of fish. In selenium-poor areas, this innovative method can be implemented in aquaculture to improve breeding outcomes. Se concentration should be adjusted to the chemical compound, fish species, and Se’s content in the yolk.