At 40-45mm the male should have coloured up. If they are happy with the
tank conditions the male should show obvious gold colour in the body and at
least a trace of blue at the base of the first dorsal. I have found that in
a community there will be one dominant male and the others will remain
subserviant - however they will still show a pale blue in the dorsal. Mine
show that colour from about 25mm on. My females always have that mottled
appearance and never have colour in the dorsal.
From: John Grylls <jgrylls at bendigo.net.au>
To: rainbowfish at pcug.org.au <rainbowfish at pcug.org.au>
Date: Friday, 8 August 1997 20:54
Subject: [RML] Sexing desert gobies
>I have recently purchased a nominal pair of Coward Springs desert
>gobies, the "male" is about 40-45 mm in length, and the "female" is
>5-10 mm shorter. They quite are similar in appearance and behaviour,
>sparring and displaying on occasions.. The larger fish has a slightly
>more yellow head, and I think that I can convince myself that his head
>is flatter and proportionately larger, but there is not much in it.
>Their differences could be explained by sex, but I suspect it could
>also be explained by differing levels of maturity. Neither fish is
>sufficiently mature for genital papilla differences to be apparent.
>Any opinions would be greatly appreciated.