zebrafish sex ratio

Petra Jackson p.jackson at dhi.dk
Mon Aug 26 09:59:19 EST 2002

From: Petra Jackson, Master's student at DHI Water and 

My colleagues and I are using zebrafish for Ecotoxicology 
research. We are developing test for detection of endocrine 
disrupting chemicals, specifically chemicals with estrogen- and 
androgen- like properties. The end-point of this test is shift toward 
one or the other sex, based on what chemical zebrafish are 
exposed to during the sex labile period. It was brought to our 
attention that different strains of zebrafish may have different sex 
ratio, which may cause some problems in standardization of the 

1) Did you observe in your work with zebrafish uneven sex ratio 
which differs from one strain to another?  

2) Do you still believe that sex differentiation is not genetically 

3) In our laboratory we have fish from two different sources. If we 
send you a sample (as described on your web-site), would you 
check if our two types of fish are the same strain?  

Thank you for your cooperation.

Petra Jackson
DHI Water & Environment
Agern Alle 11
2970 Hoersholm

Telephone: 011 45 4516 9343
E-mail: p.jackson at dhi.dk

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