Gonadotropin-releasing hormone analogue multiple injection potentially accelerated testicular maturation of male yellow catfish (Pelteobagrus fluvidraco, Richardson) in captivity

The potential for accelerating testicular development and final maturation of adult male yellow catfish (Pelteobagrus fluvidraco, Richardson) in captivity was evaluated by using gonadotropin-releasing hormone analogue (GnRHa) multiple injection, and its possible regulatory mechanism was explored by measurements of luteinizing hormone (LH) and steroid levels. The results showed that GnRHa multiple injection increased gonad-somatic index (GSI), the sperm count and the milt-testis index (MTI) and promoted the larvae production by elevated rates of fertilization and hatching, and lowered the rate of deformed larvae. Meanwhile GnRHa treatment decreased the percentages of spermatogonia and spermatocytes, increased the relative sperm density (RSD) and percentages of spermatids and spermatozoa (STZ), suggesting GnRHa treatment could accelerate meiotic division and enhance the formation of spermatids andSTZ. Moreover, pituitary and serum LH, as well as serum T levels were increased after GnRHa multiple injection. Taken together, the present study demonstrated GnRHa multiple injection successfully accelerated the testicular development and maturation of male yellow catfish, which was mediated by the increase in serum LH and T levels that further mediated biological and histological changes of testis. Therefore, GnRHa multiple injection could be a valuable method to induce precocious testicular maturation of adult yellow catfish with gonadal developmental arrest in captivity.