THE EFFECT OF MAGGOTS ADDITION TO THE COMMERCIAL FEED AND A NATURAL DIETOF EUROPEAN GRAYLING (THYMALLUS THYMALLUS L.) SPAWNERS ON EMBRYOS SURVIVAL TO THE EYED-EGG STAGE

摘要

A rearing experiment was focused on the effect of the type and diet composition on the European grayling (Thymallus thymallus L.) eggs quality, expressed by the embryos survival to the eyed-egg stage. Three feeding variants were analyzed. Spawners from group I were fed exclusively trout feed, group II received trout feed with maggots and fish in group III foraged on natural feed. A statistically significantly higher survival rate was determined for the eggs produced by group III spawners (84.57%) compared to the other two variants: 48.44% for group I and 56.00% for group II (the Tukey's post hoc test, P < 0.05).