Journal of Environmental Biology

Effect of a non steroidal tamoxifen on the gonad and sex

differentiation in Nile tilapia, Oreochromis niloticus

Author Details

Ruchi Singh

National Bureau of Fish Genetic Resources, Lucknow-226002, India

A. K Singh

(Corrosponding author)

National Bureau of Fish Genetic Resources, Lucknow?226002,India

e-mail : aksingh56@rediffmail.com

Madhu Tripathi

Department of Zoology, University of Lucknow, Lucknow- 226010, India

Publication Data

Paper received:

09 February 2011

Revised received:

18 August 2011

Accepted:

16 October 2011

Abstract

The effect of different doses of anti-estrogenic chemical was studied in a cichlid Oreochromis niloticus on mortality, growth, sexual development and sex differentiation. Percent mortality (5, 10 and 10) appeared to be dose-dependent.? All groups of tamoxifen (TA) treated fishes exhibited significant growth as compared to the controlled fishes. Immature fishes treated with TA at 200 mg l^-1, showed lower gonado-somatic-index (GSI) (male 0.137; female 0.118) than control group (male 0.138; female 0.122) of fishes. Ovarian and testicular differentiation was adjudged by the appearance of the ovarian cavity (ovary) and the efferent (sperm) duct (testis), respectively. Sex and sexual maturity of individual fishes were determined using standard histological method. Tamoxifen treatment to the fry (yolk sac absorbed stage) of Oreochromis niloticus in the dose of 200 mg l^-1 for 60 days produced 90% males and 1% intersex population. Results suggested masculinizing action of tamoxifen reversing the sex of genetic female tilapia.

Key words

Tamoxifen, Sex differentiation, Masculization, Gonadal structure, Oreochromis niloticus

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