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Masculinization of adult Gambusia holbrooki using 17α-methyltestosterone: a case of recapitulation of protogyny in a gonochorist?


Tran, NK and Kwan, TN and Purser, J and Patil, JG, Masculinization of adult Gambusia holbrooki using 17α-methyltestosterone: a case of recapitulation of protogyny in a gonochorist?, Biology, 11, (5) Article 694. ISSN 2079-7737 (2022) [Refereed Article]

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Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons 4.0 International (CC BY 4.0) license (

DOI: doi:10.3390/biology11050694


17α-Methyltestosterone (MT) is a synthetic steroid that has been widely used to masculinize many fish species when administered early during larval development, however, reports on its efficacy on adults is limited. To this end, this study investigated the efficacy of MT in the masculinization of the eastern mosquitofish (G. holbrooki) at two adult stages (maiden and repeat gravid females). The treated females were fed control or respective MT incorporated feed (0–200 mg/kg diet) for 50 days. Effects of the hormone on secondary sexual characteristics, internal gonad morphology, expression of the Anti-Müllerian Hormone (amh) gene and sexual behavior of the treated females were investigated. The results showed that MT at the dose of 50 mg/kg feed stimulated secondary sexual character development, upregulated expression of amh, formation of testicular tissue and a shift in the behavior similar to those of normal males, prominently so in treated maiden gravid females. Post-treatment, long-term observations indicated that only two masculinized females reverted back to being females and gave birth to young. Induction of masculinizing effects in most individuals suggests that the sexual phenotype of this species appears to be highly plastic with potential to sex reverse at adulthood. This in combination with its small size and short reproductive cycle could provide an ideal system to explore the mechanisms of sequential hermaphroditism in fish and contribute to genetic control of this pest fish.

Item Details

Item Type:Refereed Article
Keywords:pest fish, protogyny, hormone, sex steroid, eastern mosquitofish, Methyltestosterone, Anti-Müllerian Hormone (amh) gene, gonopodial development, testicular tissue
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Fisheries sciences
Research Field:Fish pests and diseases
Objective Division:Environmental Management
Objective Group:Fresh, ground and surface water systems and management
Objective Field:Control of pests, diseases and exotic species in fresh, ground and surface water
UTAS Author:Tran, NK (Ms Ngoc Tran)
UTAS Author:Kwan, TN (Dr Tzu Kwan)
UTAS Author:Purser, J (Associate Professor John Purser)
UTAS Author:Patil, JG (Dr Jawahar PATIL)
ID Code:149936
Year Published:2022
Funding Support:Australian Research Council (LP140100428)
Web of Science® Times Cited:1
Deposited By:Sustainable Marine Research Collaboration
Deposited On:2022-05-01
Last Modified:2022-10-27
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