Abstract
Gonadal differentiation of Tilapia aurea fry reared under various photoperiods was studied. Histological sections were made of fry gonads from the first free-swimming day through day 20 from samples taken every other day. Three feeding treatments were used for each photoperiod: no hormone, 17-[alpha]-ethynyltestosterone, and 17-[alpha]-ethynyl-estradiol. Statistical analyses show no significant difference in percent of differentiated and non-differentiated fry among the photoperiods. There also was no significant difference in size of fry for each feed treatment among the photoperiods. Fry treated with 17-[alpha]-ethynylestradiol initiated differentiation four days earlier than females not receiving hormone. Males fed 17-[alpha]-ethynyltestosterone initiated differentiation two days earlier than non-hormone treated fry. There was no significant difference in percent of differentiated to non-differentiated fry by age but there was a significant difference in size by age. Differentiated fry were significantly larger than non-differentiated fry. Fry treated with 17-[alpha]-ethynyltestosterone were significantly larger than male fry not receiving the hormone and females, which included both those fed 17-[alpha]-ethynylestradiol and those not given this hormone. Females fed 17-[alpha]-ethynylestradiol were not significantly different in size from females not receiving the hormone.
Kittler, Marjorie Cynthia (1985). Interactions of hormones and gonadal development of Tilapia aurea fry. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -596424.