Skewed sex ratios and Androgens (STOP USING ACRIFLAVIN!)

["David Lains" <david at zfin_org>]

Hello All

While searching for info about chemically changing the sex in zebrafish I
came across this: Applied Fish Pharmacology by K.M. Treves-Brown, 2000
Kluwer Academic Publishers. On page 244 chapter 18: Sex Control section B:
Androgens. Verbatim:

b) Androgens:
The androgen usually used is methyl testosterone (MT).  It is practically
insoluble in water but is soluble in alcohols.  It is obtainable as a powder
and for immersion use it may be formulated in the same way and at the same
concentration as oestradiol, but the usual concentration in the diet is
3mg/kg and hence the initial concentration in iso-propanol should be 3mg in
200ml.
A large number of synthetic and natural oestrogens and, more particularly,
androgens and have been tested for this use.  One such androgen,
11-Beta-hydroxy-androstenedione (OHA), has the advantage claimed for it that
it is a natural hormone, but it has been found generally inferior to MT and
has not so far been adopted commercially.  As a general rule the synthetic
androgens have proved both cheaper and more slowly eliminated.  Among the
later, 12-Alpha-ethinyl-testosterone and mibolerone are notable.
(NOW IT GETS REALLY INTERESTING!)
Some non-steroidal compounds have sex controlling effects on fish.
ACRIFLAVINE, which is a mixture of ACRIFALAVIN and proflavin, will
masculinize adult mosquito fish and has an androgenic action on tilapia at
doses equimolar with MT.  Tamoxifen, which is an anti-oestrogen rather than
an androgen, is also active in tilapia.
end of section.

Now it sounds like there's an interesting experiment that could be done here
if someone has the time.  All I know is I'm glad I don't use Acriflavin and
my DAG MON throw an equal sex ratio!

Best Fishes
David

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