Studies On Gonadal Development Of Discus Fish And Effect Of17α-methyltestosterone On Its Gonadal Development

Morphological observation was conducted on the gonadaldevelopment of artificial cultured discus fish, and histological observationwas conducted on the gonadal development by conventional paraffinsection. The main results are: Ovarian development of discus fish could bedivided into6stages. Oogenesis could be divided into5phases. Thedevelopment of oocytes in ovary is highly asynchronism, this is consistentwith its characteristic of multiple spawning. Under the condition ofartificial breeding, ovary of fish with9months of age developed into Ⅳstage. At the same time, female has reached sexual maturity. Testis ofdiscus fish belongs to the lobular type. The development of testis is alsodivided into6stages. Spermatogenesis undergoes spermatogonia, primaryspermatocyte, secondary spermatocyte, spermatid and spermatozoa. Underthe condition of artificial breeding, testis developed into Ⅴstage whenmale reached10months of age. At this time, male has reached sexualmaturity. Female reached sexual maturity one month earlier than male.Gonadal development and reproductive capacity of discus fish under the condition of artificial breeding are better than wild type. Atresia of oocyteswere be finded in this experiment. Operation of change water make thefishes stress reactive at artificial breeding conditions may be the reason ofatresia. So, feeding pattern of discus fish need to be further improved.Hormone feeding experiments were carried out on red spotted greendiscus fishes. Healthy fry breed from a pair of parent fish were randomlyselected and divided into four groups, feeding in four aquariums of samespecification respectively. Three of the four aquaria feed “beef heartburger” that contain17α-Methyltestosterone and the other one feed feed“beef heart burger” that not contain17α-Methyltestosterone as controlgroup. Content of17α-Methyltestosterone in “beef heart burger” ofhormone treatment groups are20mg/kg,40mg/kg and60mg/kgrespectively. Duration of hormone treatment is28d. Starting time ofhormone treatment is31days after spawning. Water temperature in thecourse of experiments was28~30℃. Three repetitions of hormone feedingexperiments were conducted. Continue to raise to about8months of ageafter hormone treatment, and then count survival rate and measurebiological character and determination of sex. Compared body colour,total length, body weight, GSI and sex ratio of hormone treatment groupswith control groups respectively. The results show that body colour weremore bright after the fishes ate food that contain17α-Methyltestosterone. Total length, body weight, GSI or sex ratio have no significant differencebetween hormone treatment groups and control groups, indicate17α-Methyltestosterone have no impact on growth and gonadaldevelopment when content of17α-Methyltestosterone not exceed60mg/kg.