Premium
Plasma thyroid hormones and hepatic nucleic acids in relation to sex of tilapia Oreochromis niloticus
Author(s) -
FontaínhasFernandes A.,
Gomes E.,
ReisHenriques Ma. A.,
Coimbra J.
Publication year - 2002
Publication title -
journal of applied ichthyology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.392
H-Index - 62
eISSN - 1439-0426
pISSN - 0175-8659
DOI - 10.1046/j.1439-0426.2002.00329.x
Subject(s) - tilapia , biology , oreochromis , medicine , endocrinology , thyroid , triiodothyronine , hormone , nile tilapia , nucleic acid , stocking , methyltestosterone , body weight , zoology , fish <actinopterygii> , biochemistry , fishery
Tilapia has a sex‐related differential growth between males and females. This trial was conducted in order to test the relationships between growth, plasma thyroid hormones and hepatic nucleic acids levels of two tilapia Oreochromis niloticus groups: one all male group that was treated with 17α‐methyltestosterone and a untreated group with males and females. Tilapia (average weight 9.7 g) were raised at a stocking of 30 fish per tank and fed a 35% protein diet for 215 days. The mean body weight of the all male group was significantly higher than that of the control group (P < 0.01). No significant differences were observed in plasma thyroxine (T4) and triiodothyronine (T3) levels, hepatic ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) levels between the two groups during the entire trial period. After 5 months females showed plasma T3 levels and a RNA/protein ratio higher than males of the two groups, and the differences were significant in the final phase of the experiment (P < 0.05). These results suggest that the observed differences were linked to the greater development of female gonads in tilapia.