Senegalese sole males born and raised in captivity (F1 males) do not spawn naturally and typically display lower gamete quality when compared with wild individuals. Broodstock nutrition is an important aspect when dealing with reproduction because it influences not only fish health, but also gamete and progeny quality. The usage of dietary algae antioxidants to improve fish reproduction is under-explored, especially in terms of the male reproductive system. In this experiment, 6 % of a blended meal of Phaeodactylum tricornutum and Gracilaria gracilis was incorporated in Senegalese sole broodstock feed, to evaluate the effects on sperm quality of F1 males throughout the breeding season. RNA-seq was employed to assess differences in the gonadal tissue of fish fed the algae supplemented diets.