New data on the possibilities of controlling reproduction in teleost fish by hormonal treatment

Some recent findings concerning hormonal treatments inducing or accelerating final stages of gametogenesis in some teleost fish are reviewed. In the rainbow trout and northern pike detailed research using in vivo and in vitro techniques led to a better understanding of the endocrine control of final stages of oogenesis. As a result, exogenous hormonal treatments, composed of a piscine gonadotropin administered alone or followed by 17a-hydroxy-20?-dihydroprogesterone injection were found to be effective inducers of precocious oocyte maturation and ovulation in the carq trout and pike. In all species fertilization rates of ovulated oocytes were high (more than 75 %). In the males of the trout, the pike and the goldfish, treatment with fish gonadotropin or with steroid hormones stimulated spermiation.